yeah this right here is key.
i played a debonaire and really enjoyed it but if you're not going to try to ambush enemies with charm (which is great fun and is where debonaire shines at wrecking enemy kith encounters), the accuracy penalty is really going to work against your desired playstyle.
different named DoTs will stack. (some DoTs will stack with themselves, but they are less common) toxic/gouging/nannasin/deep wounds will all stack.
i think the things that many people will find underwhelming about poisons on a higher difficulty is that a lot of easy to make ones target fort (which, while not as annoyingly high as in poe1, still tend to be hard defenses) and there's a severe action economy to them in combat, coupled with a bug where you have to consciously disable AI [or be in stealth which implicitly disables AI] or your character will ignore your usage of potions and instead do whatever their autoattack or AI script dictates. on potd especially you need a lot of alchemy points to get favorable accuracy/damage/duration scaling on poisons, they've been hit so hard with the nerfbat.
however, i find that Corrosive Soul Essence is a good all-purpose poison - extremely easy to make [spirit residue is real easy to come across] becomes super plentiful with BoW, does raw damage (less sensitive to needing lots of PL to penetrate enemy AR) and targets will, which you can easily debuff in a bajillion ways - a simple way is just to have your rogue use a club with bewildering blows [and clubs are +5 acc and are fast weapons]. (note: the wiki says it needs a mushroom too, but in my memory it only needs spirit residue and rune powder, which is why it's so easy to make. worth double-checking in game).
if you apply it before ambushing an enemy with an attack (careful application makes noise), or if you apply it combat while still stealthed (and you get a -85% recovery bonus) you get rid of the action economy problems of trying to use poisons in combat, and dodge the buggy AI issues.
other poisons can have their uses but are more niche or harder to make so i use them more sparingly, and hopefully with a morningstar debuff.
edit: direct PL bonuses are a real good way to improve poisons - they get around the half-PL-per-alchemy penalty so effetively are worth double their value in alchemy points, and poisons do scale generously (all of damage, duration, PEN, accuracy)
you can try weapons that are not axes but also have a dot. dagger -> true love's kiss, for example (and is slashing dmg).
assassin's slippers are great for any stealth/ambush build. it's hard to get re-invised in fights, and assassin's slippers gives it to you for free. even just once in a fight can be huge.