Killzone 2 is the first FPS with a first person cover system, as far as I am aware. There have been other cover systems in the past for FPSes, but they usually zoom out to the third person, like in RSV.
As for which one will be better, who knows. I think they'll both kick serious ass, though.
I'm personally looking forward to Killzone 2 the most out of all upcoming shooters at the moment, but I will be playing Gears 2 at a friends house the day it comes out. :D







