What is the "hardest" chord defined by? Finger placement, or finding a suitable use for it in a song? I heard somewhere that the "F" chord is one of the fewest found in the more popular songs.
To me, the 'hardest chord' would have to be determined by the finger placement. Once you have grasped that, finding its use in a song will be easy.
I am looking forward to being a great guitarist; I am still getting my feet wet.