the best 360 exclusive?

I dunno.  The original Gears of War has a special place in my heart, even though Gears of War 2 is, on paper, superior in every way. 

I think I'd go with the safe choice and say Halo 3, but Dead Rising is a solid choice, too, in my book. 

Uhh.... Right now, I'm leaning towards Gears of War 2. Halo 3 could be my choice for runner-up. Banjo ranks up there too, I think.

It would have to be Gears 2.  Banjo maybe, but I have a feeling that might go over to the pc for some reason.

For me personally that would definitely be Crackdown. But also the whole Gears-franchise is quite high on my list for that category (if you mean exclusivity compared to the PS3 :-) )

i havn't played many but i would say fable 2

If you want racing, then there's Forza 2 and PGR4.

I hate X box but I have to say Gears.

Alan Wake is going to own everything on the PS3.