1. Nintendo 64
2. Sega Dreamcast
Although I've never played any games on these it won't stop me from trying. I'd really like to see here some games from PSX, but they would need the original BIOS and Sony is not known for kindness so I guess it's out of reach. What a pity!
On a side note: I believe it's hard to find and publish new games these days (with many developers closed or sold), so your options may be drying up now, and the consoles will add the new blood. I wish you luck! It's good that this place will eventually become the ultimate source for good games. Thank you, guys!

1. SNES
2. N64
3. Sega MegaDrive/Genesis
I doubt Nintendo would come on board, though. Not that I own a Wii, but I remember hearing about being able to purchase older titles to download from Nintendo..? Did that ever go ahead?

1. Dreamcast
2. Neo Geo
3. Mega Drive

1. Super Nintendo
2. Sega Genesis
3. Arcade

1. Amiga
2. Commodore 64
3. Super Nintendo

1. Genesis
2. N64
3. Dreamcast

1. Amiga
2. Mega Drive
3. SNES

1. Amiga
2. SNES
3. C64

1 - Arcade
2 - NeoGeo
3 - Sega Dreamcast
Why? Well simply because I can already purchase Nintendo and Commodore 64 games on Wii Virtual Console. Oh, and because The Typing of the Dead is just too awesome. :D
I know that you can also buy some arcade and NeoGeo games too on Wii Virtual Console, but the selection is very sparse for now.

1- Amiga: Amiga was an amazing computer, sadly no one remembers it, only consoles. Everybody talks about Megaman, Metroid, Mario, but no Cannon Fodder, Superfrog, Gods. So Gog must fill this empty space.
2- Arcade: Arcade machines have a huuuge game archive. A Mame-like platform would be wonderful. Unlimited coins, 4-player multiplayer, endless fun.
3- Super Nintendo: My most favorite console. It has very good games in it. And because of "cartoony graphics", the games don't look blocky blocky like that early 3D games.

1- Dreamcast
2- Nintendo 64
3- Sega megadrive 2

1. Sega DreamCast
2. SNES
3. SegaMega Drive / Genesis

1. Neo Geo
2. Arcade
3. Sega Dreamcast

1. Amiga
The Machine I didn't have but my brother had. And would not let me play it. That bastard.
2. Commodore 64
Machine which I had but envied the sounds and graphics of my brothers Amiga.

1. C64 (So many games!!!)
2. Amiga
3. Neogeo