Hmm, controversial opinions?
Well keep in mind this is all opinion, just personal preference. I've got quite a few of these.
Every Metallica album after "...And Justice For All" is almost completely unlistenable to me.
Dream Theater are all amazing musicians but most of their music is boring.
A lot black metal friggin sucks in terms of musicianship and skill but it's still a genre i love.
Grindcore is mostly noisy but still talented.
Opeth is both amazing and overrated.
Michale Graves era Misfits is better than Danzig era. (yup)
Iron Maiden is good but also ridiculously over rated.
Death Metal (and it's subgenre) is the most talented form of metal besides prog metal.
Slipknot is an alright band but a lot of their songs are shit.
I love all forms of metal but deathcore is one of the best live, along with, death metal, thrash, and metalcore.
Tech Death is more talented than most other forms of metal.
Deathcore is a form of metal. Yes it is a good one. Yes there are shit bands in it. Yes there are amazing bands in the genre as well.
Same with metalcore.
Breakdowns have their place in metal and are amazing live.
Tim "Ripper" Owens is a better vocalist than Rob Halford how is is NOW, young Halford, no.
Early Cradle Of Filth is black metal. Saying Cradle Of Filth are a black metal band is a somewhat true statement as they once were.
Dimmu Borgir can still be called a black metal band.
The order of the Big Four from best to worst is
1. Megadeth
2. Metallica
3. Slayer
4. Anthrax
Does this mean i like them the most in this order? No.
Suicide Silence is a METAL good band.
Thats all i can think of for now.