The Beyerdynamic DT770 Pro, 250 ohm, closed back have the least bass of the three to me. These were what Sweetwater recommended for tracking and mixing.
Beyerdynamic DT880 Pro, 250 ohm, half open back have more bass than the the DT770 Pro and sound more even to me. I think the DT880 Pro may be the most even sounding of the three. Listening to music on them sounds good also.
Beyerdynamic DT990 Pro, 250 ohm, open back sound the fullest of the three to me, especially in the upper bass and low mids. Listening to music on them sounds great also.
Just plugging each of the three in for the first time, I'd immediately liked the DT990 Pro best, followed by the DT880 Pro, then the DT770 Pro. After listening to music through each of them and playing my Axe FXIII through them all night I still feel the same, but I found I really like the DT880 Pro a whole lot also. I found I dialed in presets a little different on the DT880 vs the DT990, but I was able to make them both sound great.
Testing them out and dialing in presets I found if you have any cuts on the lows or highs in the cab block the headphones sound completely different so I turned off the cuts while I was testing. I found I often didn't need them.
You are definitely going to dial in your presets a bit differently with each of these sets of headphones (just like if you did the same with different studio monitors). I am going to take the same preset and dial it in with each set of headphones then see how they each sound on my studio monitors and powered PA cabs next.
These headphones are very comfortable to wear.