I have them both, I love each of them for their own specific reasons. But, I half to give Last Resort the edge here. Like everyone has said the graphics are amazing as well as the sound track. I personally love the controls of the game charging the orb to track the walls is killer. The only gripe I have is the second loop this isn't freakin Ghost N' Goblins. I usually turn it off after the first loop has been beat, such a drag to half to do it again.
Things I like about AM2 the armor upgrades are very cool. The flame thrower I think is the most powerful and best "for me". I love the "Black Hole" armor upgrade this is so cool never played a game where you get to create a black hole to send your enemies into. : ) But, it's not a very good weapon, I like the stage bosses some are very creative.