POE2 has dumbed down combat system of previous game, that somehow ended up more uneven in terms of difficulty (mostly too easy) than POE1. +POE1
Main story in Deadfire is worse- it is three quests long nonsense, without any payoff (spoilers: there is no cool bossfight, you die instantly if you try to pick one with Eothas). Gods with cool designs building up your confrontation with Eothas and it ends in you going "Dude you are Wrong/Right/RightbutgivepeoplesomethingtomakethemstrongerObviousBestChoiceHere/KillEveryone" and he either goes 'Dude, you are right" or "Dude, you are wrong". Yeah, main story in POE1 is also garbage, but it has more content and variety (and bossfight). +POE1
In POE1 you have: Eder (Humor), Grieving Mother (Drama), Durance (Religious Lore), Kana (Geographical Lore), Aloth (Garbage), Pallegina (...). First three are well developed character (Eder's quest goes nowhere though), others suck but there is reason behind them existing.
In POE2 we have Serafen (Humor), Eder (Humor), Tekehu (Humor), Aloth (Garbage), Palegina (Why?), Xoti (Female Eder). Most of your companions have the same personality traits and despise violent behavior and unlike Tyranny or AP (where negative rep with teammates gave some bonuses) you get only negatives if companions hate you, leading up to them leaving your party. So be a good boy and don't play excessively violent, anti-religious asshole or you will lose 4-th of the game's content. +POE1
Ui and Graphics are way better in POE2. +POE2
Writing is the same shit, but most of the annoying lore is hidden behind hyperlinks. Player replies sound worse in Deadire, but there are more of them and they actually lead to different outcomes. Sidequest are better, due to them being more complex and having wide variety of solution. +POE2
Factions. Yeah, those are obviously better in POE2, because the whole game revolves around them. Pirates, Valian Traders (which would be the best faction by default, because their leader is the only one who supports long-term development of science and education, so Devs decide that they are slave-traders to make them unattractive to player without putting any effort into doing so), Deadfire traders (Military fanatics), Huana (So these have no redeeming qualities and they have cast system, where one asshole decides whether the newborns life will be shit for the rest of his life or not, with promise of rebirth in higher cast). Pirates have the best quests (both subfactions), Valians and Huanas are fine in this regard, but i do not remember a single Deadfire Trader's quest and i have done them all. Also faction quests cross with each other in interesting conflicting ways. +POE2
I am not counting voice acting as Pro for POE2 because it sucks.
I like POE1 better to be honest- it was first Obsidian CRPG project with quite low budged and did well for what it was. POE2 had way more resources, but, arguably, ended up only slightly better than POE1.