G12H30's do sound exactly like you're describing, OP. The fizz was the first thing I noticed about them as well. They have a great low end, and without the fizz they'd probably be one of the better sounding speaker you could get for 2x12 cabs or smaller, but the fizz pretty much kills my opinion of the speaker in general.
Personally, for all things high gain, I've always had the best luck with the classic pairing of V30's and Greenbacks. V30's will give you a tight low end and great upper mids while minimizing the fizz. Greenbacks can have more papery fizz going on in the top but the mids are huge and rich, and you could probably low pass the highs away pretty easily. My favorite flavor of Greenback is the Heritage Greenback though, now known as the EVH signature speakers, which sound like regular Greenbacks but with the fizzy highs smoothed out and mostly filtered away.