My own personal line in the sand is what Wikipedia calls “the sixth generation”: Sega Dreamcast, Nintendo Gamecube, Sony PS2, Microsoft Xbox. They’re “retro” to me. Starting from the seventh generation, there was a noticeable bump in the ability for systems to churn out relatively-realistic graphics, with the PS3 and Xbox 360 leading the way, and the Wii embracing its delightfully-modern cartoony style.
See also https://lemmy.blahaj.zone/post/175172 :)