Woof, tough question. I really like traditional and non-traditional RPGs alike. If S.T.A.L.K.E.R. doesn't count I'd have to say Divinity: Original Sin 2 even though I still haven't finished it. I also am playing Disco Elysium now which is pretty damn good.
My favorite RPG game is Genshin Impact because of it’s exploration aspect and as well the story and the lore it has for every individual character.
Currently Genshin Impact is at version 2.3 and there’s a new character that has been released.
Arcanum was good in many ways, great story and characters, and it was for a very long time the best steampunk game, the world was superbly created.
Impossible to name just one... Will probably forget many, but at least Fallout 1-2, Planescape Torment, Baldur's Gate 1-2, KOTOR, FF7, Dragon Age: Origins, Persona 4 are other RPGs I enjoyed greatly. Does Nethack count as RPG?
Divinity: Original Sin 2 is the best multi-player RPG (outside MMORPGs) I've played, it was a great experience with a team of 4. We played for months (usually 1 session per week).
I haven't yet played Witcher 3 or Disco Elysium, here's hoping they are future additions to the favourites list. Oh, and even Fallout: New Vegas is still waiting...
Far too many to count but it's a tie between World of Warcraft and Baldurs Gate. WoW owes a lot to BG, but I have to admit that when I played BG twenty years ago at university I wasn't into action games, but now I need action elements to really hold my attention.