I'm terrible at guessing first week sales so I'll just do lifetime.
Gears of War 3 - 7 million
Gears 1 and Gears 2 are basically tied at 6.13 & 6.14 million units respectively. I bet with some good advertising, and this being the last game in the trilogy, that Gears 3 could do about 7 million.
Skyward Sword - 6.5-7 million
It will be well hyped and probably get great reviews, but seeing as how the best selling Zelda ever sold 7.6 million, and that's Ocarina of Time which is considered the best Zelda game, I see no reason to think Skyward Sword will sell that many even with the Wii userbase being way higher than the N64 userbase.
Uncharted 3 - 5-5.5 million
So Uncharted sold 3.5 million, then Uncharted 2 sold 4.4 million. I'm betting now that the Uncharted series has a reputation as a fantastic series Uncharted 3 could match Uncharted 2's sales on hype alone, then if the reviews are great it could go on to sell about a million more than Uncharted 2 did.
I'm going against the grain saying first week and lifetime will both be won by Gears of War 3. I'm gonna say Uncharted 3 pulls the best reviews though (even with the fact Zelda games get high ratings b/c of nostaliga)
