Alexandria, VA
I have had both. Logically, I think SM is better, because it has more to do, better rules, and is just a great game. I don't remember the quotes, but man is it serious "My Rosie's dead". JJ does some fun work though. 
Emotionally, AFM is better because the callouts are hilarious and the dots are great. The Martian attack is sweet. It is a straight up fan layout though, and the rules are what they are.
I got rid of SM because I wasn't playing it as much as my other games, but I wouldn't mind getting one again. I don't think you can go wrong either way.
