For the most part, the people I know who like metal are particularly deathcore enthusiasts, and that enthusiasm has introduced me to all the deathcore/sludge/ambient black metal grouping alongside my appreciation for lighter stuff such as Iron Maiden or Dream Theater. Generally nowadays if I make a playlist to listen to on a journey, it's composed of mainly rough-edged production, such as Slipknot, Nine Inch Nails, Job for a Cowboy, Whitechapel, etc. Really, tune and melody aren't necessarily the selling points of an album for me, but the overall feel of dirtiness and, more rarely, a genuine sense of grittiness. It's perhaps a difficult thing to pin down because I have different preferences for difference genres, within and without metal, but I think if there were any uniting factors that describe what I like, it would be hard-hitting brick wall mastering and a good beat you can jump up and down like a metalhead on a trampoline to, sitting around very sparsely edited guitars. Which ends up being not too far off most black metal bands, one particular example such as Behemoth's O Father, O Satan, O Sun (after about a minute of intro).
On the other hand, I have no music education, other than what I've taught myself (through trial and error largely), which is perhaps why my songwriting is generally rather makeshift, following more what interests me more than what conventional successful artists' writing would suggest. In fact I try to, as I'm well aware of the rise of djent and post-metalcore as supposed genres, and I've no intention of going down that route, on the basis of knowing that is what many bands are doing. It's possible that (somewhat unintentionally) my choice to write black metal as opposed to anything else was influenced by the fact that so few new bands are doing that type of thing, even less so in the UK. I know a fair number of the local rock and metal groups where I live, and there's absolutely nothing resembling black metal here.
By the way, I think it's worth saying that I genuinely appreciate your taking an interest too - it really does mean a hell of a lot that you're taking out the time to respond to this, especially that it's not your preferred taste