I never really played Halo 1 that much since I didn’t have a good PC at the time it came out for that version (really bad trust me), and never had the friends at home locally to enjoy the first game.
Halo 2 was a big jump up in graphics from the first game, and they did add a lot of new stuff like dual wielding and energy swords now. The single player was enjoyable but kinda left you half empty. I liked playing as Master Chief, I thought Arbiter’s bad guy turned good story-line was uninteresting and stupid. If I’m going to play as a alien you killed a ton of in the last game, then I want to kill humans not other aliens.
The multiplayer is why I was hooked on Halo 2 for so long. So many maps by the time I got to it, and so much fun. Slayer, CTF, all kinds of modes, and some of the best maps in Halo history. I really sucked at the game at first, but it eventually made me a decent Halo player and I can hold my own in Halo 3 and Reach.