For me it was encapsulated by doom 3 for the most part. Games with strong dynamic shadows like splinter cell chaos theory and stalker with a mix of shiny specular effects is timeless for me. When I go back to these games the shadows still feel as good as they did when they came out and the lighting perfectly crafting the mood. A lot of modern games now even though their fidelity on paper is much better just always feel extremely flat to me and don't pop out of the screen like they used to. It seems like they're missing contrast and UE5 seems to make this even worse where all the games using it just look like mush
I don't care about graphical fidelity much and if anything I like 'worse' graphics because it usually means better performance. Chaos theory, Gta 4, and Kingdom come I think all look great. I still like how Halo 1, Kenshi, Grim dawn, and Bannerlord look though. I think art style and direction matter more.
if i had to point to a single game though it would be shrek 1 on the xbox.