The same can be said for any genre of music then. Any genre of music encompasses a range of stuff that can range from difficult to easy. So this question in un-answerable.

.....I think when it comes down to your specific list the delineation between prog and punk is very very important.

The list is definetly flawed but I chose classical because I was assuming it encompassed everything considered "classical" music. There is no way there is any thing "harder" to play than composers like Beethoven, Mozart, Liszt, Bach, Rachmaninoff. They require not only extreme techinique, but also deep understanding of music, and an understanding of oneself as a performer.

Yes, well stated.

true jazz musicians can rival and even surpass classical music in melody and technicality.

There's a lot more to take into consideration than just melody and technicality.

^ agreed. i think the hardest genre to play would be the one that runs counter to your natural playing style the most.

for me it's country, any time i try it, it comes out funky. like honky tonk raggae.

I'm a rock drummer and have been since I started playing when I was like 10. In my opinion jazz is the most difficult because by the scores I have read, its playing rock but backwards. I mean, instead of snare on 2 and 4, its on 1 and 3, with a lot of improv. I'm sure if someone first learned drums from jazz it would be easy, but to switch from one to the other takes some time.

I said jazz mostly because of improv, but it is also the most fun.

Jazz hands down if you're an instrumentalist, but I've often quipped that the voice is the hardest instrument to train.

Classical music has the capacity to be more difficult than anything else.