Definitely Halo 3. More random nonsense crap happened in that game than any other in my experience. Also the BR never felt quite right to me in that game. Killing someone with it just never felt good the way it did in Halo 2.
Halo 2 because I was younger and had an anger problem, plus I played it wayyy more than any other halo.
I remember so much crap like host br 4 shotting you from a mile away while yours took 10. Meleeing someone then watching them melee you a second later and dying. Looking at the guys back and having him assassinate you. Noob combo, etc.
Love the game but it drove me nuts sometimes.
Halo 3 on the other hand was less love/ hate and more hate/ hate. Nothing pisses me off more than crap hit detection.
I'm older now so I don't rage much in reach or h4 though some things do still piss me off. Boltshot. *shudders*