Halo 3 will sell more.

You're comparing apples to oranges, though. SMG is a single (well, 2) player game and Halo is a game which will heavily focus on online multiplayer.

Compare it to SSBB, another game with a heavy focus on multiplayer. I'm sure SMG will be excellent, but you don't buy SMG with the intention of playing it for 700+ hours like my friends and I have with SSB games in the past.

At least 15 mil. for SMG, for it's lifetime sales.
At least 9 mil. for H3, for it's lifetime sales.

IGN got some hands on time with super mario galaxy...

http://wii.ign.com/articles/803/803958p1.html

It sounds like game of the year...

I think that Halo 3 will not sell as well as some people would think because of the competition in the FPS genre. There are so many freaking FPS around nowadays that I can't see halo doing INCREDIBLY well... which it would need to do if it were to outsell galaxy.

Galaxy is going to be on a hole new level then ANYTHING that has ever been seen.

I think it's a matter of lifetime vs 2007. I think that H3 will win 2007, but SSBB will win overall because Wii will have larger install base

Mario is going to win. Sunshine is the ONLY main series Mario game not to break the 10-million barrier (SMB2 reached it with combined sales of the 2 versions, and SMB, SMB3, SMW, SML, SML2, SM All-Stars, SM64 and NSMB all reached the mark as well.) And Galaxy seems much more like a "true" entry than Sunshine did. Let's put it this way: Sunshine selling slightly below Halo 1 levels was seen as so pathetic it was like a scandal for the Mario series.

One thing people need to consider with Mario is the co-op mode. Mario is certainly a "gamer's game," but its one of the most accessable gamer's games too. At Thanksgiving and Xmas this year, there's going to be a lot of kids or teens playing Mario, who hand Mom or Grandpa a second Wiimote to play sidekick. All they have to do is aim and click. Mario Galaxy's co-op is literally designed to be played together by one "gamer" and one "non-gamer." This is the X factor, as far as I'm concerned.

Even with a price cut, the price barrier for Halo 3 is going to be much larger than it was for Halo 2, and 360's momentum just isn't very good. The first two barriers Halo 3 needs to cross are Halo 1 sales and Halo 2 sales, before we even think about it selling 10 million. If it doesn't sell 10 million, it really has no chance of beating Mario Galaxy.

I do think Halo 3 will pass 9 million and take a run at 10 million in the long run. But I think Galaxy will do at least as well as SM64 (12 million), though not as well as NSMB (should do 14-15+ million).

I think Halo 3 vs. SSBB would be a better question. I really don't know what I'd pick there.

 Also not true.  I'm not getting Halo 3 and know a good deal of people who own a 360 that couldn't care less about Halo 3.  Not saying that a large percentage of 360 won't get Halo 3, but, well, I just think you're wrong in thinking that SMG and Halo 3 won't both be similar in that a very large percentage of the consoles owners will be getting those games.

 And kind of contradicting myself here I realize, but did that on purpose (makes sense in my head somehow).

Why on earth not?  NSMB is facing at least as much competition as SMG will be in the long run. 

Now, the short term is a different story.  SMG is launching at a time that consumers' pocketbooks will still be recovering from MP3, and bracing for SSBB -- not to mention RE:UC and NiGHTS, the latter of which launches the next day -- so it won't get out the door as fast as Halo 3 will. Combined with a later street date, it's 2007 sales will be easily (but not hugely) outmatched by Halo 3. 

But over the long term I think that it will have probably about the same attach rate as NSMB has to the DS, or better -- which I expect to be at least as good as the attach rate Halo 3 achieves.  Since the Wii is inevitably going to overtake the 360 in overall sales, and widely expected to keep that lead, ... well.  

Halo 3 definetly. But Brawl and Galaxy will definetly sale a lot. Over time though I think one of those games will outdo H3. But Halo 3 is the big game for 360 and really has no competition especially in the American market for 360 gamers. So with the Wii having a lot of competition especially within it's own first party that will definetly make a difference at least for this year.

Halo 3. At the press conference, they treated SMG like it wasn't a big deal. The Mario franchise has sold as well as it did since the 64 days. (not counting DS)

Super Mario Sunshine sold about 6 million because the Gamecube only sold about 20 million. If the Wii sells over 150 million, than Super Mario Galaxy could sell for 50 million, especially if it becomes bundled with the Wii. Think about it, if the Wii might defeat the first Nintendo, or better yet, the Playstation 2, than Super Mario Galaxy could have the chance in defeating its predecessor, the undefeated champion, Super Mario Bros., which has sold around 40 million. Halo 3 may sell 9 million, since the Xbox 360 is doing better than the Xbox, and it might be the only Halo game on the system. Halo 3 has absolutely no chance against Super Mario Galaxy. Super Mario Sunshine is one of the greatest games of all time, and Super Mario Galaxy will only be better. Halo is also good, but face it, the Xbox 360 will probably lose to the Wii, therefore, it only makes sense that Super Mario Galaxy will win.