I wouldn't say that Pink Floyd is overrated, I'd say that they're overplayed. While it is annoying that every high schooler drools over Dark Side Of The Moon when Animals and Wish You Were Here are so much better and other progressive bands like King Crimson, Yes, Explosions In The Sky, The Mars Volta...etc are just as good if not better, they still deserve credit for their brilliant studio work and live performances.

For overrated bands I'd go with:
Nickelback (every song is the exact same thing)
Raq (complete rip off of Phish, no originality)
Jack Johnson (not talentless but Xavier Rudd and Ben Harper are much better)