[SIB] Prototype or TimeShift?

Both of these games are on the weekly sale, and I have about five bucks to burn, so I thought I'd give them a look. What I'm mainly looking for is a smooth and fun experience with satisfying mechanics; I don't really care about the genre. I'm pretty terrible at "realistic" first person shooters, where there's lots of recoil and you need to aim down the sights in order to hit anything. Is TimeShift more like that or is it closer to old-school/source engine? Also, with Prototype, is it more of superhero/villain story or just a conspiracy story where you happen to have superpowers?