I’m thinking 2015 - Witcher 3, Undertale, and Kerbal Space Program are all classics. Fallout 4, Arkham Knight, and Cities Skylines were all excellent too, though fallout 4 and Arkham knight aren’t necessarily the best games in their respective series.
2001 or 2011.
2001 easily had the most games that were highly rated and as others have said you some real classics. The PS2 was hitting it’s stride, the original Xbox Launched, and the Gamecube was right there.
2011 also had some damn amazing games: Arkham City, Portal 2, Skyrim, Skyward Sword, Minecraft, Mortal Kombat 9, Starcraft II, Bastion, Uncharted 3, Battlefield 3 to name a few.
Dark Souls was 2011 and it was way more influential than all those games (except maybe Minecraft).
Demon’s Souls came out years prior.
as a ps3 exclusive that wasn’t even close in popularity but yes most of ds1 was copied from demon’s souls