Halo 2 is one of my all time favorite games by far. Halo CE thru Halo 3 are all tied as my favorite games in their own special way. Halo CE: First halo game ever and completely redesigned the expectations for video games, Halo 2 was the first awesome multiplayer game for XBOX Live and was fun to glitch in :), and Halo 3 was just, I cant even put into words. The custom games in halo 3, forge, the greatest multiplayer experience of all time, just an awesome game.
As for Halo: Reach, although it is not as good as the others, it is still a great game and i love to play it.
In other words, Halo 2 was pretty awesome.