Let's see, well all of them are great! It's hard to choose. My favourite one would be the good ending for MO, then the MO intro, and then the good ending for AO...
I also like the AO gamespeak and basically the main screen where you select what you want to do because of the stuff Abe says. Like when you select NEW GAME, Abe says "ok" and when you select 2 players, Abe says "follow me" and when you leave gamespeak, how Abe says "goodbye!". Heh.