I own 4 Beyerdyamic headphones: DT770 Pro (250 Ohm), DT990 PRO (250 Ohm), Custom One Pro, and DT880 Pro (250 Ohm). They are all great but for different things. The DT880 is my view the ones that are most neutral balanced in terms of eq response and best for general music listening. They sound great! Also, I almost always use DT880 when recording and for general mixing, mastering, and editing. The DT770 I almost exclusively use for recording vocals (since they are closed and have less bleed into the microphone) and for some special mixing jobs. The DT770 have very distinct highs and less than average lows – which I do not find good for general music listening – actually it can be quit annoying in that context. The DT990 are close to the DT880 – I prefer the DT880, but that may just be a personal preference. The Custom one Pro have more than neutral bass, not extremely though like e.g. Beats by Dre or similar. The Custom One Pro are good for general music listening, Youtube etc. especially if you love a little extra bass, but I never use them in the studio. Could I only chose one set of headphones and I did not need them for anything special – I would go for the DT880.
For all of them I love that it is easy to change and buy new cushions and other parts. The Custom One Pro is the only set with a detachable cable, which therefore is very easy to replace on those (no soldering or disassembly needed) and much harder but not impossible on the others.