GZA is kind of an aquired taste.
His lyrics are among the best, but let's be honest, charisma he doesn't have in spades. He can drone on sometimes and be a little bit monotone. Same with Inspectah Deck, though I still like both their work with the group and solo.(Yes, I like INS's solos)
I can understand Meth being called best, flow wise and delivery wise, the dude can outshine the rest of the group some times.