Halo 1 is definitely my all time favourite Halo game ever since 2001. Halo 1 has one of the best music, scenery, and weapons. The flood were THE most dangerous enemies in the game, since they were hard to kill and they kept coming and coming relentlessly! I remember one of the Marines to say a cuss word to the enemy and it actually got censored in the game. Halo 3 is another favourite.
I do like Halo 4. It was very dramatic and interesting with the new implements and new enemies. The only problem I have with it is that it's a little short in the campaign.
I don't think I have a dislike for any of the Halo games, except that I hated that halo 2 took out the assault rifle from the first one.