2nd Generation: Donkey Kong (ColecoVision)
3rd Generation: Super Mario Bros. (NES)
4th Generation: Super Mario World (SNES)
5th Generation: Super Mario 64 (N64)
6th Generation: Either Sonic Adventure (Dreamcast), Luigi's Mansion (GCN), or Halo: Combat Evolved (Xbox)
7th Generation: The Legend of Zelda: Twilight Princess (Wii)
8th Generation: The Legend of Zelda: Breath of the Wild (Switch)
Overall, for its time: Either Super Mario World or The Legend of Zelda: Breath of the Wild
Overall, to this day: Breath of the Wild obviously, though I'd still pop in just about any of these if the mood was right. The truly good games don't ever stop being good. That said nothing's wrong with playing more up-to-date versions of them. So those first three I'd probably play on the NES and SNES Classic, Super Mario 64 I'd play on DS, Sonic I'd play DX on Gamecube, Halo I'd play MCC, and Twilight Princess I'd play HD.
