I have a decent console collection in terms of hardware, though my game library wasn't terribly impressive until the PS2 era. Up until then, I averaged under a dozen games for each console. Since then, probably more like 3 or 4 dozen. Mainly because I never had money of my own before that and I haven't been able to go back and get everything I ever wanted for the old systems.
I just moved into a new house and am almost done getting the majority of my stuff organized, so I'll post some pics once it's all ready. Below is what I can think of at the moment with what I would consider right now my favorite game.
Items that are crossed out are those that I have either sold/traded/lost at some point. Fortunately, most of those have been replaced since then. This list is roughly in the order the systems were purchased and includes the replacement systems.
Atari VCS - Berzerk
NES - Mega Man 3
SNES - Super Mario World
Genesis + CD + 32X - Sonic 2 / Lunar / T-Mek
Game Boy - Tetris
Game Gear - Road Rash
PlayStation (PSX) - Coolboarders 2
Nintendo 64 - Mario Kart 64
Saturn - Die Hard Arcade
Virtual Boy - Mario Clash
Game Boy
Game.com - Lights Out
Dreamcast - Jet Grind Radio
PlayStation 2 - Shadow of the Colossus
Intellivision -
Game Cube - Windwaker
Game Boy Advance -
Game Boy Advance SP
Game.com Pocket Pro
Atari 2600 Jr
PSone
Nintendo DS -
PSP - Mega Man Powered Up
NES (top loader)
Neo Geo Pocket Color - SNK vs Capcom: Match of the Millennium
Dreamcast
Xbox -
GP2X
Wii -
Nintendo DS Lite
Neo Geo Pocket
Xbox 360 -
Nintendo DSi
NES
Nintendo 64
PlayStation 3 - Uncharted 2
3DS - Ghost Recon
I *think* that just about covers it. There are a few systems that I had/have multiples of for whatever reason, but those aren't included. For systems without a fav game listed, that just means I have a hard time choosing a favorite right now. I'll think about it some more and update later.
When I was a kid, we sold the old Atari VCS for probably next to nothing. I wish we'd kept it. I've since bought two Atari Jrs and a shit tons of carts for close to nothing.
I don't even want to admit what I traded my NES and all games for. I was young and stupid. I did keep Dragon Warrior 1 though because my dad an dI played the hell out of that together when I was really little and got to the end and never beat it. I'll bet the battery has died and the save is gone by now

When I checked a few years ago it was still there, though. I should try that this weekend. Trading this off and regretting it is the reason why I haven't sold or traded a single system since then, unless I had multiples for some reason.
My original Game Boy was lost or stolen one year at a family function. I'm guessing stolen.
My original N64 was left at a girl's apartment once and I never got it back cause we got in a fight and I never saw her again. She got my Mario Kart 64 cart as well as my special edition gold controller that I won in a Mario Kart 64 contest through Nintendo Power
My original launch day Dreamcast was left at a friend's house...we're no longer friends...'nuff said
I don't let people borrow shit these days
