There are much better exclusives on Xbox compared to Playstation. Uncharted and Killzone? Meh...
Have you even played Uncharted and The Last of Us?
Halo was good up Halo 3 (for me, that's when Master Chief's story had ended), but then MS just had to keep milking the franchise to death. They're doing the same thing with Gears. Besides, most people who play either of those franchises aren't playing it for the stories. They just want to prove how badass they are with online and on co-op.