Pros: sound, design, (unique)
Last year I bought Beyerdynamics DT990 Premium with 250 Ohm in a custom design:
I really love their design (Of cause, I also designed them in some way :p)!
The opportunity to create your own, unique style for these high end cans is pretty cool.
You can do this on beyerdynamic's website, but it's probably a bit more expensive than in other shops.
(besides the cost for your design).
I love the not-so-neutral sound, with slightly more highs and bass.
The bass isn't boomy at all, it's very precise.
I wasn't sure about that before my order, but know I'm satisfied.
Normaly I'm listening rock or techno.
These were my first high end cans, so I can't really compare.
If you're considering to buy new hifi headphones, you should definetly keep them in mind!