PoE for me is 30 months away from my mind and I sadly have to say that, while I thoroughly enjoyed the writing AND the game, I can not recall a whole lot of any quest or the main story. Some fragments remain, like Aloths personal quest that I really liked. I also really liked, in terms of simple writing, that the shield Eder was using throughout my entire game, was a pantry door, which was just a stroke of genius and the most unique weapon I have seen in a RPG especially in PoE which lacked memorable items.
Speaking of this, something similarly awesome, but much more present, is Lilarcor, speaking two-handed sword in BG2.
As far as quests go, I think the Elder Scrolls and Fallout Series (all of them) offered a lot of totally ridiculous quests, something which I enjoy. The pornstar quest in Fallout 2 comes to mind, or the Last Voyage of the Constitution in Fallout 4, the battleship manned by robots.
On more serious topics, ME2 and 3 allowed you to heal the Genophage a virus that made a certain alien race sterile, which has a huge impact in the forthcoming centuries. So basically everything that leaves you a choice, but with no immediate effect on the gameplay. Also Tyranny offered similar things, where you could totally go your own way, side with one, all or no factions, but it would mainly change things in the power structure, not in the direct gameplay unless you worked for it really hard.