Planescape: Torment
I go back and forth on this one all the time but even without the 90s edgelord concept of killing your own mortality to make you immortal this one still holds up as greatest story ever told. The setting is incredible, the best D&D has ever offered, and while the plot has been rehashed in other media it's still compelling, in films such as Shutter island, but the best was of course Memento. If you replaced the antagonist (your own mortality) with any whisker twirling BBEG you chase throughout the adventure across literal hell, losing your memory every time you "die", doomed to repeat the same events over and over again, the story still holds. It's sort of like a reverse groundhog's day. The day keeps resetting, but only for you. Everyone else remembers you, has went down this path with you a thousand times before, has fought and bled and suffered with you, all resigned to their fate, stuck in, from their perspective, a never ending time loop with you none the wiser.
Honorable mentions
Vampire TM: bloodlines
Morrowind.
Witcher 3
Dragon Age: Origins
previously comments I concur on, if any Mass effect belongs on the list its Mass Effect 2. And KOTOR2? jfc. If any KOTOR game belongs on the list at all it's actually The Old Republic (the MMO). Think of it as 100 hour single player RPG with 8 unique new game + modes, it delivered a better story than either KOTOR. KOTOR suffers from the same 90s edgelord problems that Torment suffers from, ohh look the bad guy has amnesia, btw you play as the bad guy, how clever.
So yeah that's not quite 10 but close enough.