What on earth is speedcore and Terrorcore? And I assume you have a stereotype that all metal is like Slipknot / Disturbed / whatever other crap comes to peoples minds.. when you mention metal. Or for hip hop Souljah boi, 50 cent and Insane Clown Possese.. Theres excellence in both genres.
I've heard quite a bit of metal - and I guess I just don't like the sound of heavy guitars. OK, the occasional metal song is OK, but anything heavier - heavy, death, black, etc. is just not for me. I can appreciate metal though - I can tell a good song from I bad one (I hope

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Hiphop - well, of course modern hiphop is terrible. Soulja Boy is pretty much the king of terrible music. I have heard the vintage, vinyl, sampling stuff and hiphop isn't really my thing at all. Still, I can appreciate the old stuff. None of the radio crap though. Eugh.
If you enjoy classical and jazz then you ought to appreciate the technicalities of metal, at least. What do you mean by soundscape/ambient? Jakob? HDU? Operation Rolling Thunder?
I don't class genres by the sound of a band. Heck, I don't listen to commercial music much. I go for the amateur free stuff...
Ambient is a ridiculously broad genre, but by ambient, I would mean something like this:
Nehir
Drum n Bass is rubbish, it really is.
About d'n'b - I really don't have a clue as to what the commercial stuff sounds like, but from the couple I have heard, it sounds pretty awful, and pretty generic. The dnb I tend to like more (once again, the amateur stuff, generally from Acidplanet

) is the drill side:
Matsumoto
Robovirtuoso