As always: all depends on your's party. Zealous Focus is worst because this doesn't provide unique things, especially if you have priest in party. +6 ACC? Priest eventually will give +20 ACC with Devotions of Faithful at per encounter basis. Early in game melee ACC has no big advantage (you will miss or graze a lot, for example in raedric's keep), if you able to survive bit more hits: your's attacks anyway will eventually hit (eventually graze or hit over enemy paladins to be more correct). Bigger ACC is extremely useful for spells. But again, it is important early game. Later - if your's debuff spell is graze - you always can recast it on already debuffed target - and this time this will hit with bigger chance statistically or by already applied affliction(s). If you fight against dragon - you ANYWAY will have one or max two chances after this to apply all your force over it. I.e. 4 disabling spells is usually more than enough (some classes has "infinite" number of them...).
But, i'm always pick Gallant's Focus on my MC melee wizard at level 2: it is not so good as weapon focus, but it is also applied for spells. Later savage attack will be like -1 of base acc, so it is good talent. I.e. ZF is also good talent, but...
I'm like Zealous Endurance much much more, because even on PotD any 10 PER character has enough accuracy anyway, even with upscaled content. In that terms i'm say that Zealous Focus is not a good at all (at least for me). I'm just prefer bigger defenses: one of my easiest parties was be:
1. Melee Frontline Wizard (!!! limit self !!! to only low level spells, and for any beams, i.e. up to 5 level spells, chill fog is super powerful all game, but any self-buffs are valid regardless to level (martial power)) (MC), shield + sword (last blade of the white forge)
2. Melee Frontline Paladin (Zealos Endurance, Marker + Cladhaliath crafted for marking and coordinating) = +20 ACC for someone
3. Melee Frontline Wizard (Bittercut + shield, same - limit spells, but any self-buffs are valid)
4. Ranged Wael Priest (Rod of Pale Shades), painful interdiction = reliable stuns with this rod
5. Blast Wizard (Golden Gaze) = blast + penetrating blast = you are top 3 auto attacking damage dealer (any wand/scepter actually work)
6. Chanter (Her Courage Thick as Steel - ONLY, and before 13 lvl only fortitude and reflex buffs, no dragon thrashed or other "cheesy" stuff like +25% fire damage for everything including spells)
Front-line wizards are targets for use duplicated little saviors. This party are very strong: health loss is really becomes comfortable because damage are spreaded, wizards can use infuse of vital essence when need, and others (like paladin) has no this spell, so you need rest because of this members. When "Her Courage Thick as Steel" becomes available - this makes any physical fights are easy (you will laugh into face to any pack of ogres), and you really need worry about enemy DoTs/raws (and i'm hate in game this spells/abilities - why anyone should wear heavy armor if we/enemies do raw damage?). I'm hate mostly part of game when you become strong enough almost without armor (you choose armor for some special enchantments, not for DR), and worry only about raw damages. Surely - if you disable enemy first - you doesn't take damage. This is why i'm hate disables in both ways. Afflictions - is good. Disables - is bad. Disables break fights.
Don't forget to get at least 3x Gridle of Driving Wave = each frontliner can do knockdown once/encounter (in my taste - it is still a belt! item which can be replaced to +3 CON or +3 MIG belt easily - really good i'm prefer 2x/encounter gridle), otherwise it is really strangle choice. But even if 1/encounter knockdown it is gives more control on battlefield. Also casting spell break engagement, while knocking down is not. This mean, that you will not lost flanking bonuses in some cases. Also knockdown is faster. For example enemy want you "clear out", but frontliner knockdown it before. There is very important/useful in my taste. Actually for me much more useful than any other belt in game.
I'm like wizards in this game, but really i'm miss something like "Stonefist" from DAO. I.e. simple single-target CC or Damage/CC.
I'm absolutely ignore any firearms. They are had been cheese for cipher. And i'm dislike firearms with magic. So... i'm just not use them and happy. Also, i'm absolutely dislike idea about paladin's FoD with ranged weapons. FoD is should be something strength-based (touch-based) ability. Why firearm weapon's damage should depend from innate abilities of holder? This kind weapons can use only accuracy, but not additional damage. With touch weapons is another story for me, because wielder of weapon and ability is "same thing", sword continue body, and body is sword. Only this way paladins can work in my taste of word. Any way, it is not a problem in game, because i'm just not use this ranged FoD's or other things.
And this my party are strong: chanter provides "physical" shield (i.e. non-DoT 30pt shield for every time as it chant (depends on level)), two little saviors + outworn buckler gives +15 to all defenses. This together makes you very-very-very strong, that literally means that front line wizards really acts as meleers and even very rarely needed in Llengrath displaced image to be protected. Instead they always cast alacrity of motion and smash in melee. Also i'm get to anyone Appertince's Sneak Attack = +15% damage boost is... worth it. Wizards can put afflictions easily. But, even more simpler is just flank enemies, - this hard when you keep formation, but any teleporters inside formation will be flanked. And again, wizards and priest easily enable sneak attacks.
Well, so why Zealos Endurance is exceptional: it is +3DR (which is not main thing, but still very good, and there is better than Armor of Faith because you not need to cast it), but it is +15% Hits to Graze (and this is stack with +50% Hit to Graze of Llengrath displaced image). As i'm mention above - Graze->Hit (Zealous Focus), Hit->Crit conversion is something that good, but it is can't be compared to incoming Hits->Graze: eventually your's attack rate will be near "zero-recovery", and you will score hits or crits any way - we anyway will debuff or lock targets. Even flanking is already debuff. With marking of paladin - is even more simpler. So you eventually anyway will do hits and crits to enemies. But, there is nothing what can score up incoming hits->graze reliable as paladin aura. (Wizard's spell / potion of displaced image only, but they still stack, and early - it is main thing why other solo wizards rely on this spell without any stupid hardened veil talents - they always completely waste = you not need have too big deflection early because you will not have enough power to destroy enemies fast enough anyway, later = displaced image is only buff which enough to survive any battle (of course, it doesn't make you invulnerable - but some combinations puts near about, again, it is my preference - some peoples likes veil, but i'm not - it is cost 2 talents with very low output in my thoughts)... For example, if you strong enough to reliable "handle" summon weapons, i.e. spirit lance (i.e. win without shield), - then you already has enough tools to do same with good old sword and shield in own hands. Short-term tactics is bit different, but absolutely doable in both ways (keep in mind, that in hard fights deflection is not a problem - you can be stunned/petrified/paralyzed/charmed/etc).
Well. So ZE, also allow priest to not cast their bit better "armor of faith" spell. Actually (for me) best 1-level priest buff is Holy Meditation (because this provides buff for concentration for whole party (and even this rarely needed)). Mmmm.... I'm never play with "min-max", i'm play with max parties. I.e. never put nothing below 10. Game has already enough points to score primaries like INT/DEX/MIG (INT > DEX > MIG). MIG not needed at all. I.e. all my favorites is 18 INT/17-18 DEX/rest in MIG. Why? Because my wizards(!) (i.e. with lowest base ACC) with savage attack can reliable hits anyway with right tactics. I.e. without priest buff. Even if you will have 20 MIG is make only +30% damage that still not enough on 20DR targets. To breach 20DR foes you need +100% damage, in that case you will deal 20-30 DMG per hit. And this is really reliable only with top gear. Prior this point, you anyway will get exceptional gear - so damage already will be ok. And "fat" targets anyway will be destroyed with magic. No matter which class - as i'm understand - all melee especially soloers do game with scrolls.
Priest buffs i'm think that should be used in cases when you face enemy which use this spells against your. For example lagufaeth broodmothers casts minor avatar and devotion of faithful. In Iron Flail against you "form of helpless beast" will be applied! Or even call to slumber! So, if against you this spells are used: i'm thing you are free to counter with same or similar spells. Otherwise again - you be too powerful, because having any paralyzer in party (wizard who know ninaguath shadowflame), or even worse (!!!! game challenge breaks to zero) - you have cipher - then... I'm played with cipher and liked them a lot. But after some moment, i'm can't stop self from paralyze and do phantom foes on foes. And... this alone drops challenge to around zero. This is why i'm stick with beams on melee wizards (bitter mooring for example is exceptionally good spell, fire beam also good, but it is shorter range, but in WM is more applicable due to frost immunity).
Ugh. Sorry, i'm wrote much more than had in mind. I'm had in mind this minds for another post...
Thanks Boeroer! I'm read too many your posts... and... i'm now looking for funny small party (preferable melee). now even 2 wizard + priest PotD + Upscaled is looks like too easy for me (i'm abandon one of walkthrough with only 3 wizards, may be should restore). But, yes, if we has priest in party - challenge drops. For me Priest is not as ACC buffer, but more like afflictions disabler. Something we can do via ring, something via scrolls. But with priest we doesn't need scrolls. For me - playing as eldritch knight is important part. For example, divinity original sin just doesn't allow make good this kind build because sword require strength, and full hybrids in game doesn't goes well. PoE - allow you do anything you want, and i'm like it! Unfortunately PoE's wizards are very-very-very limited in my mind. Even they debuffs: had too many debuffs, but they has limited spells which can utilize them. For example - 1-2 level spells are vs fortitude. Trying to debuff 120 fortitude guy - is already hard task. Even if foe will be debuffed - it is not a fact that wizard can reliable can apply damage spell. On other side of course lot of deflection/reflex spells. But, again: i'm doesn't like pure disable spells - they always like cheese. I.e. sure, shadowflame + any reflex-based spells is a winner combo. But... vs fortitude spells potential shines only when you buff own accuracy: you rarely can debuff fortitude reliable. (in my opinion). Of course, wizards had very good and good vary of offenses, they generally they had almost all kinds of debuffs, but they are no have any sense if you can't apply them. At time when you can reliable rely on them, you already has access to something high-level like chromatic orb which acts as chillfog: i.e. damage + debuff/disable. Priest spells in my opinion is counterwise - i'm can't understand why Pillar of Faith does damage for target and in AoE makes prone. Why Pillar doesn't prone target and does AoE damage? Just physically... It is very strange if you hitted by concrete block, and after it was happend you will find that you still stay, but all around is prone. )) (Again, similar "stonefist" need here)
PS: I'm hate druids. Returning storms looks cheese. But on other side, returning storm casts very-very-very slow, so actually before it can be casted, it should be guarded, as i'm seen. Anyway i'm hate druids because they are innate shapeshifters. I'm strongly belive that shapeshifting abilities is something that is not depends from class. I.e. "lycantropy" disease can allow you shapeshift, some spells can allow it (i.e. casters are great shapeshifters... in home cats), but innate shapeshifting... meh. Any beside this, i'm dislike druids. And even more dislike druids as enemies. BTW: priests/wizards has no saves against druid attacks (infestation of maggots or similar). But druids has! Of course, power party should include druid to cast something protective (moonwell and protection against poison at least).
Thanks everyone who had been patient enough to read to end.
PPS: May be before PoE2 has sense to take small "dynamic party" with story companions? I.e. for example do not take more than 2 story companion in a row... not sure.
PPPS: On other side, my dream BGEE/BG2EE party was is F/M, M/T and C/M - unbeatable trio with right tactics even with SCS. This is of course understandable: having 3 good casters which viable in melee - is always cheese. But, it is funny, if you bored/doesn't more like standard companions. I hope in PoE2 multiclass will be very good. Or... hope, that multiclass will not be worse that in PoE1. So many games makes from wizards are "typical" mage users, that you become hate them (i.e. like in DoS - hybrid are most powerful, but you should invest in one school anyway, otherwise you will truly master of none, and never will be jack of all trades).