Covenant
In Halo you have to fight against a lot of very different enemietyps: Elite (yout picture), Grunt, Jackal, Brute, Hunter, Drones
and that are only the Covenant- there are still the Forrunner Drones and the Flood
In Killzone there are Hellgast and...?
My vote: Covenant
BTW: When I read your GT5P vs FM2 comparison I thought the next would be KZ 2 vs Halo 3, but in the grafical departement. This is the much better comparison- the GT5P vs FM3 was very pseudo.
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