One of my favorite metal subgenres is technical thrash.
A lot of people seem to have the idea that tech-thrash is little more than conservatory wankery, with endless show-off riffs that go nowhere and an overemphasis on structure at the expense of actual songwriting. But that ain't so.
For instance, check out this cover of "Eleanor Rigby" from Realm's 1988 debut
Endless Wafare.
How fucking metal is that? It's pure class. Yes, the riffs are technical, and the solos are elaborate, but they don't feel like they're just sort of stuck in the middle of the song. And they're infinitely more complex than the Beatles' original.
Here's an original song, "Mayday In Kiev", off of the Texas tech-thrash act Watchtower's 1989 release
Control & Resistance:
Again, it's a deeply structured song; the riffs build on each other, but they have an end-point, a logical progression from one note to another. And it's a ridiculous song. I adore the lyrics:
In a nation for a dangerous penchant for secrecy
A dread disaster at Chernobyl was concealed
As a poisoning cloud spread over the Eastern Bloc
Alarming information was reluctantly revealed
An explosion in Reactor Four - a fire refusing to cease
No containment walls preventing radioactive release
Evidence that peaceful technology had gone awry
More catastrophically than Windscale or TMI
METAL! Anyone can write about dragons or dwarves; it takes a special kind of creativity to turn a historical disaster into a raging piece of thrash.
And there's St. Louis's own Anacrucis. I love these guys. They excelled at a clinical, highly cerebral sort of thrash that didn't so much focus on technicality for its own sake as for the sake of atmosphere. E.g. "Still Black" off the album
Manic Impressions.