I'd argue that progressive rock, jazz, and classical all have more technical prowess, as you put it, than any type of metal. Other than that though, metal is definitely ahead of the game.
Jazz is dumb. Anything labeled progressive usually sucks, no matter how good the players are. On the other hand, classical is totally badass, and classical guitar is awesome. I have a friend who totally shreds who's starting to take classical guitar lessons and it's improving his overall playing significantly.
You said technical prowess, not if it sounds good. Jazz is basically right behind boy bands on my list of the fruitiest music ever, while it can be fun to play and improvise
in moderation. If I play jazz for more than 5 minutes, I feel homosexual and that I should go to a gay bar.
As for progressive, Symphony X and Dream Theater are fucking amazing. It really depends on if the band can pull it off, though.
And classical, you don't have to tell my twice. I love transcribing Paganini to guitar, then throwing on some distortion for a neoclassical sound.