Depends on whatcha want. I own the DT990, the ATH-M50's, and Sennheiser HD600. I also run with a Sound Blaster X-Fi Titanium HD sound card, and a Bottlehead Crack tube amplifier.
The ATH-M50's are by far the best value out of what I own, simply because they sound good without the amp and sound card. If you're not going to get an amp, then just get these.
Also, if you're using these for commuting at all, you'll want something closed by like the ATH-M50's. The Beyers are open back and will leak some sound.
All that said, I only use the 990's when I'm listening to bass heavy garbage like EDM. Otherwise I prefer my Senns that should have more neutral tone, closer to the 880's. I was actually wanting 880's, but found a craigslist...