Only played Halo 1 and MW1, but Halo was significantly better IMO. AI was much better (and few/no infinite respawning enemies CoD is known for IIRC), wasn't just scripted event followed by scripted, good enemy/weapon design IIRC, good music, a campaign that took more than a few hours to beat, and a story/universe that isn't forgettable. Not exactly fair since I haven't put a lot of time into the games, but based on what I've seen/read/played, Halo is a much better franchise. Though not really the biggest fan of either. I prefer other FPS games to Halo, though I did enjoy Halo 1 quite a bit (enjoyed Marathon more though). I do hate both games for setting some "standards" that developers are now afraid to change (more so Halo I think, though CoD isn't helping). Health regeneration and carrying only 2 weapons sucks, outside of maybe a few specific situations. As an example, Insomniac screwed up big time in copying this scheme for R2.
