Chaplain Fenix
It's entertaining if you can find a game full of people around your skill level.
Or if there were other game types than TEAM RUSH THE LONGSHOT SPAWN.
I enjoyed it when it first came out because it was a game I could play with all of my friends without getting my a** kicked. I never had an XBox, so Halo was out of the question, as were most online PC games because my computer sucked at the time. (I played in the Halo 3 beta; that was just painful.)
Gears was the first game where I could join a bunch of my friends, set it to maps such as Warehouse that weren't "RUSH THE LONGSHOT," have a ridiculously close sniper vs. lancer battle then dance around my opponent in his down state before putting a grenade on him then curbstomping so that it looked like my stomp made his head explode.
... but that was pre-patches, and I haven't played the game in like 3 months because there's no real fun or originality left to it, at least to me.