If we are counting PC (which we should) a lot of those aren't exclusive...
In fact, 360 doesn't have many exclusives if we count PC (again, which we should)
The main reason I don't own a 360 is because almost every single good 360 game ends up on PC (I've been playing Gears and Viva Pinata the past few days on my PC).
I know every RTS listed up there is on PC as well (Universe at War, World in Conflict, Command and Conquer 3 Kanes whatever) and they will be much better on PC as well.
Here's a video from my band's last show Check out more (bigger) videos here http://www.youtube.com/user/icemanout