Coldplay is undeniable! Probably not on my list of the greatest, but they have made quality music over the years. My favourites are Fix You, Spies, Yellow, Trouble and they have many other good songs. Check out their discography:
http://www.song-list.net/coldplay/songs. you can play each of their songs on Rhapsody using that link.
That being said, as a band I think their best days are behind them. They are making almost pure pop now - I guess for artists that is the price of fame.