Let me start off by saying that this is my first review and that I'm reviewing these headphones off of 2ish years of listening. This review is also going to be rather short and concise.
I moved to these headphones from Grado headphones so please excuse the criticism of the soundstage if that isn't of concern to you.
I'm going to get right down to the meat: the best genre to listen to with these headphones is hands down vocal trance. Listening to countless albums of Armin van Buuren, Above & Beyond, and many more Armada (record label) artists has convinced me that my opinion is indeed true. These headphones excel in thumping mid/upper bass accompanied with warm male vocals and singing synthesizers. These headphones will sound miles better when listening to vocal trance than any Grado headphone.
If you have M50s... do yourself a favor and please take a listen:
EDM also sounds great:
However, these headphones do not deliver in genres that require soundstage - something that is lost in closed-back headphones. Classical, jazz, any acoustic music for that matter sounds compressed and unimpressive. The mids hide behind a thick blanket of bass while the treble sings with no audience to connect with. Individual instruments are hard to define as if they are in another language that must be translated in order to be understood. There is no happy medium between strings and brass – they are all the trying to talk over each other. In addition, trap music lacks in terms of hi-hats. Hi-hats tend to sound distorted with the M50s. Other than that, trap/hip-hop should sound fine with the warm, crisp bass that these cans produce.
On the other hand, solo piano pieces sound warm and full. The need to pick out individual instruments and sounds is no longer there. As a longtime pianist myself, I really do enjoy listening to Chopin, Beethoven, Brahms, Ravel, Debussy, and so many more on the M50s. The M50s seem to shine when it doesn't have to decrypt numerous sounds occurring at one time.
To wrap things up: buy these headphones if you like tight, thumping mid/upper bass. They do tend to lack in low bass (with eq, however, they produce deep bass just fine). I would strongly recommend a Fiio portable amp to improve some aspects where the M50s fall short.
I hope you enjoyed my review. Please be nice! This is my first one! :)