Floyd: I'm a fan. They were experimental, innovative, couragous. But not the most gifted musicians, if that's the criteria.
But if less is more, then they are up there. It's not what you put in, as Louis Armstrong said, it's what you leave out.
Compared to Yes in that way, they come off better. I can't listen to Yes anymore, at least not anything post-CTTE. More musically talented band, but lost their edge, and ceased to be a rock band. And Anderson's has got to be the world's biggest new age pansy.
To go to the other end of the spectrum, I think Black Sabbath was an underrated musical group. My cousin put on a live tape, they have chops.
Zepplin was legitimately a great group, 3 great musicians and a great singer. Cream likewise. Duane Allman is rocks greatest slide guitarist. RIP. I wish he'd made more than one record with Clapton.
Songwriting was never as strong, but for pure musical ability, it's hard to match Red era King Crimson. Or Discipline era Crimson for that matter.
Prince is an underrated musician.
Now days, all those "musician" bands that formed prog bands are either in metal bands like Dream Theatre, which I always had trouble getting into (never could headbang to 7/4 time) and jambands like Phish, Moe, Lake Trout, ect.
And ooh yea, Peart's a great drummer. He makes Rush worthwhile.