As of right now, Gears, but that might change after Mass Effect.

Assassins creed, Crackdown, Saints row and CoD 4. Those are the only other games I own for the 360 right now. I don't wanna pick which one i like the best though =P

My 5 favorite 360 games:

1. Test Drive Unlimited. There's no comparison - I have spent most of my 360 time playing this game. I love being able to drive on the island of Hawaii - jet down the H3 ... there's nothing else that grabs my attention than this game ...

2. Rock Band. RocketPig sings its praises - and I agree. The game is worth its salt. Seriously, you may *think* it's not worth it, but believe you me - after playing it solo or with a couple of friends, you will have some serious doubts about playing GHII or GHIII again ...

3. Call of Duty 4. I was in love with COD2 - it was the reason I bought a 360. COD4 follows in its footsteps. A solid FPS that does sooooo many things right ...

4. Ace Combat 6. Though it's a stretch to imagine a jet carrying over 100 missiles, free flight makes this one sick title ...

5. Elder Scrolls: Oblivion/Mass Effect/Bioshock - all 3, especially Oblivion totally rock, but I can't play Oblivion that much because it soooo just sucks you in ...

I will admit, 2007 was the year of the 360 software. I can't remember recently a holiday season with soooooo many AAA titles to choose from, for any system.

Since I don't have a 360 and only get to play at my friends house occasionally I would have to say Rock Band.

Get Call of Duty 4. Its seriously...freaking awesome. The multiplayer will keep you going once you finish campaign. Id also pick up Dead Rising, it should be like $20 now.

Want a long ass rpg that will take you forever to finish.  Get Oblivion.

@ Soriku

Oh, I loved ES, but most of the time, I am all about some racing or mindless FPS ...

I am really enjoying ES as well -- It's freaking BEAUTIFUL on a 42" HD set but you have to like JRPGs and a lot of people don't.  The turn-based repetitive combat will turn off a lot of people...

@ KN

What up, man? Yeah ... it's a pretty game. I love the visuals - I have yet to throw it up on my projector - I was on my 22" LCD. When I catch a break, I will definitely do that ...

The turn-based combat is a turnoff for me, though ... but it's still a sweet game. 

@ Soriku

Are you serious? Maybe I was popping too many Qualudes, but as much as you talk about the PS3, I just *assumed* you owned a 360. If I had some loot, I would buy one for you!

Seriously, Eternal Sonata blows Blue Dragon out of the water ...

Feel free to continue to post recommendations, but I will analyze the results so far.

Recommendations for games with more than one:

Mass Effect: 11
Bioshock: 8
Gears of War: 7
Oblivion: 5
Dead Rising: 4
Call of Duty 4: 4
Blue Dragon: 3
Viva Pinata: 2
PGR 4: 2
Orange Box: 2
Saints Row: 2
Rock Band: 2

I was leaning towards Mass Effect before I asked, and it got the most recommendations, but I just found out that it has partial nudity and sexual themes. Bioshock and Oblivion also have sexual themes, and Dead Rising has partial nudity, so now it seems it's down to Gears of War and Call of Duty 4. I think I might go with Gears of War since it's older and less expensive. Unless...

Are the partial nudity and sexual themes in the above games really that bad?

Thanks to everyone who has recommended a game, and I hope someone will answer my new question.