What would be better a B-52 AT 100 w/ Tri Mode Rectifier or a Carvin V3? The bands I like are Metallica, Iron Maiden, Metal Church, Black Sabbath, Testament, Slayer, Steve Vai, Joe Satriani. I would Probly get a nice cab for B-52 like a Marshall 1960 AV or TV.
The V3 is reportedly able to stand up to the expensive, high end and boutique amps (Bogner, Mesa). The B52 is a budget amp, a good one, but not really in the same league. I don't have personal experience with either, but from what I've seen and heard, V3>>>>>B52.

I'm kinda craving a V3 right now, so my post isn't exactly unbiased.
I will show you something different from either
Your shadow in the morning striding behind you
Or your shadow at evening rising to meet you
I will show you fear in a handful of dust
The V3 was made for the V3 cab, But Im sure any cab would sound great conected to that beast Mine does at least.
Agile Al-3000 prestige, Carvin V3 half stack, Fender 75, Line 6 spider 112, roland microcube, JT serpent, JT Sg Custom, Washburn D-100, PODXTL, Monster Powerconditioner, George L's cords
dont know much about the carvin, but i do own a B-52 AT-212. its a really nice amp, i love the cranked tone i get. but like said, its a budget tube amp. still a nice amp, but there are better ones out there. if you dont have much to spend, look into it