Mob Rules may be the weaker of the two golden Dio Sabbath albums, but it's a classic that contains two of my favorite Dio performances - The Sign of the Southern Cross and Falling Off the Edge of the World. That said, I just started listening to Be'lakor and find this album to be the strongest; Sun's Delusion is the apex and an incredible track. Still, it's gotta be Sabbath.
Megadeth, because I've never "gotten" In Flames (that whole style does nothing for me) and at least half of United Abominations is solid.
I've never heard more than a few seconds of an Alter Bridge song in my life, so when up against Motley Crue... Alter Bridge.
Priest, because I'm not a big fan of Ozzy-era Sabbath because his voice annoys me and I think their music was far more exciting with Dio.