CE because of proper Campaign balance (with exception of putting a massive number of rocket launcher Flood on the map), huge enemy numbers, and fun and engaging enemy AI, Halo 2 for level environments, Covenant side of the story, and scale, and Halo 3 for tricking. But mostly CE. That said, despite Halo 2 having annoyingly large hitboxes and a wretched Needler, I don't dislike it as much as I dislike Halo 4, which has 20x worse everything, and Reach which has 10x worse a lot of things (though it had better easter eggs than Halo 4).