Ranking of each genre's overall metalness in order from most to least:
Trad metal
Power metal
Thrash metal = death metal
Doom metal
Groove metal
Non-prefixed black metal
Prog metal
Metalcore
Alternative metal = nu metal
Goth metal = folk metal
Prefixed black metal
I'm fine with that, I was trying to be non-confrontational because if I lumped all black metal together it would have come out much lower. If you want a more thorough breakdown...
Trad metal = trad/power metal = epic doom metal = trad doom metal = speed metal = trad/power metal that is progressive
Euro-power proper = first-wave black metal = Bay Area thrash = death/thrash = OSDM (and all tech variants thereof)
Groove metal = thrashy Gothernburg melodeath = overtly melodic Gothenburg melodeath = Gothenburg-derived metalcore = crossover thrash
Stoner doom = NYHC-derived metalcore
Second-wave Norwegian black metal proper
The average pre-Dream Theater prog metal
The average post-Dream Theater prog metal
Funeral doom, plus probably other shit I don't care about that I'm forgetting
Alternative metal = nu metal
Stoner rock = grunge = hard rock
Goth metal = folk metal = symphonic black metal
Metalcore that isn't remotely metal
Depressive suicidal black metal
Black ambient
Thrash metal is aggressive and extreme for the time. It's influencial on extreme metal in general. Is Imperial Doom the same as Show No Mercy or Where No Life Dwells the same as Kill 'em All ?. Possessed-seven churches is black metal,thrash, and death metal. Does that mean thrash,black,and death metal is the samething to.
You can't possibly peg folk metal into a single tier, let alone dump it all into a lower tier than genres that are overtly non-metal like grunge and hard rock. That umbrella includes bands that are rooted in everything from epic doom metal to atmospheric black metal. Stuff like Mael Mordha belongs much closer to the top of the list.
Hell, it's plenty silly lumping all gothic metal towards the bottom. If you're looking at, as you say, Sisters-of-Mercy-with-heavier-guitars type bands, sure, since post-Wildhoney Tiamat is as much gothic rock as gothic metal. But the early doom progenitors of the style, e.g. My Dying Bride, are at about the same level as stoner doom. Early Theatre of Tragedy is not too far behind, nor is anything that has a strong doom element.
25 minute? Pah. Be real men like Sleep and make it an hour long.Writing 25 minute songs via a fairly basic traditional doom metal structure is a pretty fucking good middle-finger to the masses. It's almost like a test of will.
25 minute? Pah. Be real men like Sleep and make it an hour long.