Halo 3 on the X360

Grand Turismo 5 on the PS3

Uhm, WiiFiit.

The user base of a console has nothing to do with the amount of games being sold, Mario 64 was packed with the system for years. GT was the second best sell franchise last gen and will do insane numbers this gen too.

Wii: Wii Fit is too unpredictable. It will either do extremely good (5-8M) or insanely good (over 15M)! Not counting the unknown factor I have to go for MK or SSBB (both near 15M). Why I think they will outsell SMG (10-12M) is because online games just have bigger legs than offline games.

PS3: Grand Turismo 5 (5-8M)
Xbox360: Halo3 (8-11M)
DS: Pokemon P/D (20M)
PSP: Monster Hunter 2 (2M)

Super Mario Galaxy.

It will probably be a game we havn't even seen yet. Like Wii Fit II!

But of ones we know, I'd have to go with SMG as all signs point to the Wii winning, and Mario will appeal to all demographics, young, old, hardcore, casual, male, female, martian (hey, it's Galaxies...). Mario games always sell extremely well, have very high attach rates and being on the best selling system will pretty much guarantee it first place.

Halo 4 for 360 (or Halo 3 if 4 never comes), and I'm going to go with FFXIII on PS3, I think GT is getting stale and has too much direct competition to be #1.

You can't predict that... as you never know what kind of amazing innovative, new game we've never seen before, but the whole world is going wild for, will release in the future. But if I need to guess... Smash Brawls. Online function, plus one of the most famous Nintendo console titles and you have a million seller. Though if you count the hand-held games as well, most definitely a DS game will be the winner above all.

I agree the userbase of a console has nothing to do with percentages, (i just wrote a similar thing in answer to you on the other thread) but it can affect total numbers, especially with such a huge difference like PS2 to PS3....GT5 will not outsell SMG/MK or SSB:B, GTA4 has an excellent chance when adding both 360 and PS3 numbers, but i doubt GT5 will get past 10 million

Best sellers by system (of games that we know of, for instance GT6 may come to PS3 and outsell GT5 for all i know)

Wii- unknown could be any of SMG/MK/SSBB/Wii fit if we are counting it

360- Halo3 even if we take away any bundled ones it will be Halo

PS3 very probably GT5

however Pokemon D/P will probably outsell all of those. 

THe best selling game of this gen will be super mario galaxy I bet. We will have to see the revies, but if it gets 9.7 average or higher it has an amazing shot at it. PS3- My guess is Grand Theft auto
Xbox 360- if there was any justice in the world- Banjo Kazooie 3: Wacky Witch World (titel is made up) would get 10/10 and be a very strong seller. But I bet it will do porryl, bet 8/10 revies, and Halo 3 will be by far the best xbox 360 game. Though I wouldn't put anything past Gears of War 2 if its amazing.