Instead of just replying by saying I hope I win, I'm going to say all my favorite things about each of the halo games (fps only).
Halo CE - epic campaign, and warthog wars were awesome as well. playing the PC version with modded maps was addicting and the game was just classic.
Halo 2 - best multiplayer maps of any halo, legendary online games, dual wielding, intense lan parties with friends, super jumps were sweet, ranking system was good (except for the hardcore modding it created).
Halo 3 - amazing campaign, very good maps, fire grenades :D and the brute chopper, flipping the elephant, epic infection playlists
Halo 3 ODST - Firefight was awesome but that's all.... (sorry least favorite halo)
Halo Reach - Best controls of any halo, the revenant, invasion, the armory, all awesome! Armor abilities were a nice addition, also killing afk's was fun.