I'm not really a metal head and I'd never heard of Possessed / Seven Churches so I found it and gave it a listen.

My honest opinion is...meh. Musically it's an interesting track, arguably better than some Iron Maiden songs, but the vocals are the same muddy mess that ruins so many other metal bands.

If you listen to Seven Churches and then immediately play "Aces High" or "Run to the Hills" you will hear exactly what I'm talking about. It boils down to this; Jeff Becerra seems to love being buried in the music so he can growl out undecipherable lyrics while Bruce Dickinson is conveying at least as much vocal power while standing out from the music and being clear enough that you can hear the message.

It's just my opinion of course and honestly this is the same problem I've had with nearly every American Death Metal band. I don't know why most of them even bother having a vocalist as they are functionally useless.

Rock out to whatever moves ya' but I definitely wouldn't rank Possessed ahead of Iron Maiden.