I prefer FUD because it had a great character arc. We saw Lasky become the character he was in the game, we had reference, we had background. With Nightfall, Locke pretty much stays the same character throughout the whole thing. A good character, mind, but he did not change much.
Although Halo 3 is the most popular "classic" multiplayer, the Halo experience has evolved far past its gameplay style, quite necessarily. Sprint, debated feature though it is, is a feature that is expected to be a given in most modern FPS games.