NES: Super Marios Bros. 3
Genesis: Earthworm Jim 2 (that's a tough one though)
PS1: Twisted Metal 2 (maybe Jet Moto 1 though, I had dozens of PS1 games, my favorite era)
Dreamcast: Soul Calibur
Gamecube: SSX3 (Wind Waker a very close second)
PSP: Locorocco (sold the thing pretty fast though)
Wii: Super Mario Galaxy
PS3: Uncharted 1
Oh and where I've done most of my gaming since I was a kid...
PC: Starsiege: Tribes, best game ever.
Bah, I hate these threads, makes me remember how much more I used to enjoy gaming back in the 90s early 00s...