Best campaign of the Halo series, and why

[Farsala]

Halo 2 of course. Best physics, best ai, funnest on every single difficulty, good variety, and fun environments.

Some fun runs that I did:

1: Legendary difficulty, nuff said.
2: Vehicle only run, squishing vehicles into doors with grenades and stuff.
3: Melee only run, going as far as hitting flying enemies with only melee...