I love A7X with all my heart, but I think MCR has a crazier fan base, so the wider-known album might be MCR's album. [Although, it might come out equal. :/ ]
Seeing as how one of the new MCR songs is called "The Black Dragon Society", or something or other, My Chem all the way. xD I'll bet you anything Mikey came up with that one. Why? I don't know. I really don't.
I don't listen to Avenged Sevenfold much (though I've been wanting to. I'm just lazy when it comes to getting CDs from the library), I think they'll do better than My Chem. My Chem is going to have a really hard time doing better than their last album, and I don't think they can do that. It'll probably be just as good, but not better.