While I've never tried Beats headphones, I have recently bought a new pair of cans.
A friend trumpeted Sennheiser HD650 and Sonarworks Reference software, which uses EQ calibration to correct the sound in the headphones.
This software has been good for my mixing, which has increasingly relied on using headphones since I realised the room I use needs treatment and I was overcompensating the lower frequencies.
Hopefully I've moved on from muddy sounding mixes like this one.
I bought a pair of HD600 after reading a few reviews and decided to draw the line at paying the extra $80.
The Sennheisers are a nice pair of headphones. I found the packaging over the top but there is a sense they provide extra detail, although they aren't as comfortable to wear as my cheaper cans.
The other headphones I have are AKG K240s, which are closed and get a bit hot around the ears in warmer months.
These AKGs are mostly used while recording but provide a very flat and somewhat clinical response, although there is a sense the higher frequencies can vary from how a mix will sound over speakers.
I also have several pairs of Grado headphones, their SR60 and SR60i and a pair of Alessandro Grado that my brother thought were rubbish and gave to me.
I used these last pair lots in recent years and like them for comfort and the flattering warm mid-range.