Well, define the genre. Let's start with that. Who's in and who's out?
Rolling Stone's Top Ten Ever:
10. Tool · 9. Pantera · 8. Led Zeppelin · 7. Judas Priest · 6. Megadeth · 5. Slayer · 4. Iron Maiden · 3. Black Sabbath · 2. Dream Theater · 1. Metallica.
LZ isn't really metal IMO, and I am not familiar with Dream Theater. JP maybe had a sense of humo(u)r. Maybe. Ozzy's solo stuff maybe too; not Sabbath.
Listen I'd say the same about most prog too, but I'd describe prog as pretentious, and metal as cynical. And prog at its worst is fatuous and lugubrious, which are easier negative reactions to deal with than those one gets from metal which for some is simply physical pain at how it grates sonically (or, for me, boredom).
That said, I listened to plenty of prog, and I still love Rush, but I know what it is and I don't find find it nearly as compelling as a) I used to and b) many other genres.