I don’t think any game has ever done potions well. In games like Diablo 2 and PoE you depend on them too much for healing and mana regen, it gets annoying pushing potion buttons almost as much as your skill buttons. In Diablo 3 it’s too much the other way, you don’t rely on them at all but there’s also no flexibility.
As Kiadaw said, I personally prefer a system in the middle of those games. Basically a Diablo 3 potion system that you don’t rely on but also one with flexibility, similar to PoE. My idea is something like a 3 flask PoE system where you can choose 3 different flasks but one where the flasks aren’t reliant on killing trash mobs and are instead based on charges that regenerate over time. Example: A health flask would have 3 charges and each charge would take 15 secs (or whatever) to recharge. If you want to make it more strategic you could make charges universal across all potion slots, meaning if you use 3 health flask charges you lock out your mana flask and other flask- this is a similar system to classic WoW where you have to be strategic as to whether you want to health potion or mana pot.
-I think it’s also important not to end up like PoE where you have to use potions to cure status ailments. It becomes a mandatory thing and the game basically becomes balanced around it.