NES = Tecmo Bowl
SNES = Super Mario World
N64 = WaveRace 64
GameCube = Metroid Prime
Wii = Donkey Kong Country Returns
DS = Kirby's Canvas Curse
3DS = Super Mario 3D Land
NES = Tecmo Bowl
SNES = Super Mario World
N64 = WaveRace 64
GameCube = Metroid Prime
Wii = Donkey Kong Country Returns
DS = Kirby's Canvas Curse
3DS = Super Mario 3D Land
A couple are ties
NES: Super Mario Bros. / The Battle of Olympus (tie here since Olympus doesn't have the nostalgia curve)
SNES: Super Mario World / Tales of Phantasia
N64: Star Fox 64 (this one is no contest, actually)
GameCube: Tales of Symphonia / Beyond Good and Evil
Wii: Super Mario Galaxy
Wii U (only owned for 3 weeks so maybe doesn't count): Super Smash Bros. for Wii U
Game Boy: Pokemon Blue
Game Boy Color: Pokemon Gold
Game Boy Advance: Golden Sun: The Lost Age
DS: Mario Kart DS
3DS: Kid Icarus: Uprising
Selling gaming accessories. Click
NES: Excite Bike
Snes: Mortal Kombat II
Virtual boy: Galactic Pinball
64: Conker's bad fur day
Gamecube: Super Smash Bros Melee
Wii: No More Heroes
Wii u: Zombi U
This is a tough pick for me for the Nintendo systems I've played the most games for, NES and SNES. I could easily choose from about a dozen for each system.
NES - Castlevania III
SNES - Zelda III
N64 - Ocarina of Time
GameCube - Metroid Prime
GBC - Link's Awakening DX
GBA - Metroid Zero Mission
DS - Chrono Trigger
Wii, WiiU, 3DS - haven't played
There's a steep drop off in my experience with Nintendo systems after SNES, so my choices are more constrained.
Might change from time to time except snes but here they are -
GB - Donkey Kong
GBA - Doom
NES - Mario Bros 3
SNES - Super Mario Kart & Castlevania (for different reasons)
N64 - Perfect Dark
GC - Star Wars Rogue Sqadron II
I gave up with Nintendo systems after this (thanks to Metroid Prime) although I have enjoyed Mario Kart 7 on someones 3DS.