Atari 7800 (Sadly, I no longer have this system, but I will have you back my beautiful Prosystem!): When I got this system my mother bought it for my brother and myself (yeah, he got it
).  We found it, along with a bunch of games, at Odd Lots (Big Lots) for real cheap.  Anyway my favorite of this first bunch was Food Fight.
NES: Obviously Mario/Duckhunt. ÂÂÂ
SNES: Super Mario World.
N64: (1st time around) Mario 64 (2nd) Zelda: Ocarina of Time
Virtual Boy: Mario Tennis and Red Alarm
Gameboy Advance SP: Street Fighter Alpha
Game Cube: Super Smash Bros.
Sega Genesis: Road Rash II
Colecovison: donkey kong
My Gamegear, Odyssey 2, Atari 2600, and Atari 5200 all came with a bunch of games so I really dont have just a "first" for them. ÂÂÂ
Here are my favorites of the first batch for those consoles.
Gamegear: Shinobi
O2: KC Munchkin
VCS: Taz
5200: Um, still no rf adaptor so I cant play.  Oh, I cant wait to spin that trackball!