MadDemiurg

Tbh I think both rogue and cipher are bad for PotD solo. They have a lot of abilities that kinda need a party and I don't think rogue's invis is enough to get by in terms of survivability. You can make a cipher tank since they have decent deflection, but you'll struggle with dps and building up focus. Best bet for cipher solo is abusing confuse/charm/puppet (allies often kill confused mobs which is great) probably. Rogue's per encounter abilites are not that great tbh + cipher's cc can be seen as a huge damage buff, since paralysed = -40 deflection alone (which also contributes to crit chance), plus cipher can target defences other than deflection with his spells. All in all, I don't see a huge difference in single target damage between my rogue and my cipher (both are min maxed). Deathblows are probably an exception, but they usually need a caster to setup. Yes, rogue single target damage is a bit better, but it doesn't make up for what cipher can do with aoe and debuffs.

You're right my druid really shines in hardest fights. I can just unequip my armor and spam aoe like blizzard and get huge advantage right at start. Dont trust the numbers on character sheet when it comes to dps it will say cipher is best coz blunderbuss bypass dr for large dmg but some fights cipher dps just cant be as good as other classes depends on the situation. Btw i'm starting to feel this game is actually well balanced coz so many people claim their class is best in their certain roles. Well done obsidian. Well, in case of cipher it's just math. He can reliably spam ~30 average damage aoe at low levels + has single target damage that is almost as good as rogue's sneak attack, without the need to flank or cc the enemy (although he has great abilities to do both of these things). In very specific situations where you are fighting a single strong enemy you can flank all the time, yes, rogue will do a bit more damage (although with high level cipher spells like disintegrate not so sure + cipher has recall agony which buffs your whole party damage by 30% against 1 target). On average though, cipher is better damage dealer than rogue. I haven't even been using blunderbuss until the mid game (mostly some combination of hunting bow, arbalest and quarterstaff), and cipher was still #1 in damage done and ahead of my rogue, even though he burned a lot of focus on CC which was helping rogue's sneak attacks.

Druid is the best AOE dps period. Wizard can maybe compete for the spot of better CC char (although Druid has good CC as well), but Druid's AOE damage is unmatched. Shifting is quite good at low level, then not worth it. Doesn't make the class any lesser though. All in all probably one of the strongest or even the strongest class.

Cipher deals almost as much damage as rogue with sneak attack (1.4 vs 1.5), but doesn't have any prerequisites for it, so it is much more consistent. Plus he has great aoe which rogue can't really compete with. All in all rogue doesn't have much on cipher imo. Melee vs range is questionable in terms of top dps, but cipher can do both pretty well. Barb's single target is lower than rogue/cipher and carnage doesn't really hold a candle to aoe spells. So cipher is a clear winner imo. But you're kinda forgetting about Druid. While he may not have the "most damage done" stat in the party (unless you rest very often) in big fights that actually matter none of the three classes above can compete with a Druid. Wizard can deal lots of damage too, but overall is weaker than druid. So for big fights Druid > Wizard > Cipher > Rogue = Barb i would say.

Ironically wizard is probably one of the better casters in terms of survivability (in terms of dps/cc/utility he loses out to druid priest and cipher imo) which can be quite useful for solo, unlike party play. Hardened arcane veil is an instant cast for +45 deflection and he also has nice spells for extra hp, endurance drain and DR. Damage isn't the best, but should be enough. Cipher can be quite tanky as well with level 4/5 spells, question is how do you get there. A lot of people seem to suggest rogue for solo, cipher basically is a better rogue. So if rogue can make it cipher can as well. But I'm not sure of either one on PotD (on lower difficulties should work fine).

Stacking deflection would work for most fights, but I think you will get fried by casters if you have low will/ref/fort. And the only class that will have high everything (paladin) deals very little damage unfortunately. Thinking that on higher difficulties you kinda need spells. Druid looks best, he is able to evaporate whole encounters in my party PotD run on his own very fast if you don't try to save spells. Lots of rest abuse will be needed of course.