They all work the same, if you test the emulator away from AM and decide which is best for you and then just tie it in to AM.
You have purists that like one emulator, you have the who gives a damm as long as the game plays.
It is down to personal taste, some people might like retroarch, others might prefer MAME.
However, AM is just a launcher, it is a front end it will load what ever you want it to load.
Regards
Mark