Personally I am looking forward to Reach the most. Its gonna be awsome after playing the Beta I think it will be far better compared to the other FPS titles. I think Reach will dominate the charts for an FPS sharing them with COD.
I will not buy another Treyarch COD. After the glitchy crappy WaW I really have no faith in Treyarch I'd much rather wait for the next InfinityWard COD. As for Medal Of Honor I have played many of the old ones but I always found they were a nitch below CallOfDuty so I won't likely purchase it.
As for KillZone3, I never played the origional KillZone, I rented the second one but found it too difficult and confusing so I decided to skip out. All the visuals in the world can't make a game enjoyable. As for Crysis I never played the first one and while it is very pretty I don't think I'll pick it up seeing as I haven't experianced the first one.
In the end Reach is my FPS of choice this fall!