For me, it's about total composition. My problem with Led Zepplin is that the verses and riffs and backbeats and whatnot will all be amazing, but then there'll be a 2 minute bit in the middle of the song that's nothing but awkward moaning or something, or the guitar solo doesn't sound like it was actually composed at all. I have the same problem with Rush, but not quite as much. A lot of great bands are ruined by a terrible singer. If one part of the band or music isn't good, then the band/song isn't good (imo).
One reason I like Cage The Elephant so much is that they manage to keep their songs sounding very fresh and unique without just being a lot of random noises. Same with Subtle.
I hate bands like Nirvana, where the music and lyrics are really repetitive, but people somehow like them because it's "deep". This is really a big example of only liking a band because of some stupid "message" instead of actual musical talent or writing skill.
A band being inspired by another band is one thing, but bands that copy a sound soley because it's popular kinda piss me off. If there is nothing interesting going on in a song, I don't really like it.
As for actual musical qualities that I like, fast tempo and a good driving beat are things I like. I generally listen to Rock, Metal, and Alternative music, but I'll listen to pretty much anything that has the qualities I like. I generally avoid Country and Hip-Hop though, along with party music and dance stuff.






