People might not like the Red Hot Chili Peppers, but they are very talented. Flea is one of the best bass players there is. And... at least they don't sound like every other band out there. Nobody else really sounds like RHCP.
IMO, Jay Z has to be the most overrated. I can't stand listening to anything he's done really. But I can't stand rap either, so there's that.
I also think Radiohead is overrated. I do like some of their songs, but not very many. I've tried really hard to like this group because everyone tells me that they are musical geniuses, etc, but I just can't get into it. So much of it sounds like just noise to me.
Obviously though, most of this thread is going to just be about what people like and don't like. Music is a form of art, and therefore it will appeal differently to different people. Some people may love a certain painting, while others hate it. It's all about taste.
Agree RHCP
Agree Jay Z (it's like people give him points as a businessman when evaluating his music)
Half agree with Radiohead. Their first 3 albums and Iron Lung EP are epic and legendary…but I think the stuff since is really overrated and doesn't stand up to those 4. Pablo Honey was solid, I wouldn't blink if someone said The Bends was the best rock album of the past 30 years, Iron Lung/OK Computer were ground breaking and amazing…then everything since is a crappier version of what they nailed on OK Computer.