SNES - lotsa games
GBC - pokémon
GBA-SP - guess it, pokémon
GC - metroids and others
PS2 - final fantasy
X360 - dunno, really!
PS3 - lotsa games

Wii - Wii sports and Zelda

DS - Nintendogs

GC - MK:DD

I haven't purchased a console for a single game. I tend to buy them when (in order of importance):

A) They have a large enough collection of games that interest me
B) They fall into a price range that I think is worth it
C) When I'm looking for something new to play

Mattel Intellivision> Christmas present when I was 4-years old...but really my father just wanted an excuse to buy a game system so he could play it.  what a sap.

Mattel Electronic Football> Hand-down from my pop... had great LED action, so real that is was, uh, well, like a few LED lights playing chase

Atari 2600> It was the hot system at the time, got it because all my friends in kindergarten has one

Nintendo DK Game & Watch> Ahead of its time.. two screen clam shell handheld from Nintendo. concept was later re-used to make the DS... Got it for christmas from some family friends

Sega Master System> I loved Alex Kidd game & Spy vs Spy (plus system was superior to the NES)

NES> Everybody had one, and of course the Mario phenomenon

Atari 7800> I thought it would be a cool upgrade to the 2600, but it sucked.. dumb comic book advertisements made it look so awesome, what a crock of sh....

Gameboy> All the great titles it had, we traveled a lot when I was a kid

TurboGraphx-16> Bonk.. I bought it 2nd hand off of my friend who didn't like it

Sega Genesis> Sonic the Hedgehog

NeoGeo> TONS of great fighter games (got it off of a friend whose parents wouldn't let him keep it... they said it was too "violent" of a gaming system, traded a spare NES and 10 games for it)

Sega GameGear> Sonic portability, and it played my old Master System games that I loved.

Super NES> Super Mario World, Mario Kart, and Legend of Zelda

3DO> Bought for me for Christmas by parents, but system wasn't very cool, actually it sucked

PlayStation> No game in particular, but I knew it was the next big thing

Nintendo 64> Brand loyalty?  It's still my least favorite system of any generation.

NeoGeo Pocket Color> The old great NeoGeo fighter games in the palm of my hand

PlayStation 2> Just had to have it because it was so state-of-the-art.. but I have always been a Gran Turismo guy, so that weighed pretty heavily

GameBoy Advance SP> Bought it for my toddler to get him interested in games, he still plays it 5 years later, and is now a gaming freak just like his dad

Nintendo GameCube> I knew that Nintendo couldn't make a system worse than the N64... mostly for the Zelda & Mario titles when it came to games

XBOX> Halo series, plus all my friends played on that new service called "XBOX LIVE" so I wanted to join the fun

XBOX 360> Tons of games that I love, and of course the greatness that is XBOX LIVE

Nintendo DS> Mario games, plus the concept sounded really awesome just like the DK Game & Watch I had when I was a kid

PlayStation 3> I was still satisfied with my PS2, but bought the PS3 for the Blu-ray player initially

Wii> Really bought it for my wife more than myself, but now I hijacked it, and so what was her's has now become mine (see how that works kids?  If your wife won't let you have something, buy it for her, and then take it back when she isn't looking... learned this move from Sun Tzu)

----

I have a bunch more systems, but I bought them off eBay to add to the collection, so I don't count those ones.  I only count the systems that I bought during its on console/handheld generation.

Nintendo consoles - Mario and Zelda games.

Nintendo handhelds - Mario, Zelda and Pokemon.

360 - NHL 08

PS2 - Don't remember.

For me, it was:

PS1- Wipeout 3/ Gran Turismo

PS2- Wipeout Fusion/ Gran Turismo 3

PS3 - Wipeout HD/ Gran Turismo 5 (See a pattern forming here?)

GBA- Pokemon Ruby/Sapphire

GC - Pokemon Colloseum

DS - Pokemon Diamond/ Pearl / New Super Mario Bros.

Wii - Wii Sports/ Mario Galaxy/ Pokemon Battle Revolution.

In short, yes I love Wipeout, Gran Turismo and Pokemon, and recently Mario plats.

NES: i played super mario bros at friends house, i had to buy it after that

Genesis: My big brother bought it for me, i liked it anyways

SNES: i bought it one year after i got Genesis, the main reason was Mario world

Gameboy: well it was the only good handheld in its time

Saturn: i enjoyed genesis so i bought sega's new console, i was not very impressed, thankfully my friend borrowed it from me and sold it for weed money.

N64: my friend who sold my saturn for weed bought it for me by force, i would've bought it either way for mario 64

Playstation: i bought it for the many great games PS1 had, i was ignoring it for years because it was new company in the gaming industry, but it just kept getting games i wanted.

Dreamcast: five words, skies of arcadia and shenmue

GBA: some great handheld games like golden sun and mario and luigi super star saga

Gamecube: Zelda Windwaker, nuff said

Playstation 2: no gamer could go without PS2

DS: the daul screen and the touch screen, and new super mario bros

Wii: the contoller, Super mario galaxy

C64 - Mum bought it for me

NES - Super Mario Bros 3 (came late)

SNES - Super Street Fighter II

PS1 - FFVII & Oddworld: Abe's Oddysee

PS2 - Soul Reaver II (which turned out to suck balls), plus dozens of awesome PS1 games but broken PS1)

PS3 - Dozens of awesome PS2 games but broken PS2

I only started buying my own systems in the middle of last generation (already had a PS2/Gamecube, bought my own Xbox), but I'll say what I wanted them for.

N64: Mario 64 (I'd actually never heard of the N64 or Playstation till my bro told me about the N64 a few days before he picked it up )

Playstation: (Don't laugh) Small Soldiers. I LOVED that movie

GBA: I just wanted a portable SNES.

Gamecube: Luigi's Mansion, Super Smash Bros. Melee

PS2: My bro and I got this for a X-mas present the year it came out--didn't really know the games

Xbox: Star Wars: The Trials of Obi-Wan, May Payne (thought Halo looked stupid until I tried it XD )

DS: Mario 64

PSP: Twisted Metal: Head On, and I'll soon have to rebuy one for Kingdom Hearts.

Xbox 360: Dead Rising, Perfect Dark Zero, Condemned: Criminal Origins

Playstation 3: ...nothing, really... got it as a present... wasn't that interested in it at the time, to be honest... was looking forward to Lair but... yeah...

Wii: The controller, Wii Sports, Zelda, Red Steel (hey, it looked good before launch, k?), Mario Galaxy, Brawl.

Current/Past Systems:

2600 - Missile Command, Millipede, etc...
NES - Megaman 2 & Super Mario Bros.
Master System - Wonderboy 3 & Phantasy Star
Genesis - Contra: Hard Corps & Streets of Rage II
SNES - Chrono Trigger & Earthbound
PS1 - Metal Gear Solid
Saturn - Panzer Dragoon Saga
N64 - Ocarina of Time
Dreamcast - Soul Calibur & Skies of Arcadia
PS2 - God of War & Metal Gear Solid 3
GameCube - Metroid Prime
PS3 - Metal Gear Solid 4 & God of War 3

Gameboy - Tetris
GBA - Castlevania: Circle of the Moon
PSP - Syphon Filter: Dark Mirror & Metal Gear Solid: Portable Ops

Future Systems:

DS - Professor Layton
Game Gear - Shinobi II: The Silent Fury & Ristar
Sega CD - Snatcher & Dark Wizard
TurboDuo - Gate of Thunder & Lords of Thunder