the reason why I and so many other people here have multiple set of headphones is because there isn't one that does everything perfectly (especially not at the $200 price point).
I have the Beyer DT 770 Pro-80 for the reasons described here: excellent comfort & amazing build quality. I can take these everywhere with me and not worry about them breaking. As well, I have the Denon's (yet, mine are the D7000) strictly for home use as I really enjoy their sound over any other closed can. I like that they don't clamp hard and that I can wear them for hours without discomfort.
You need to decide where you'll do most of your listening, and buy accordingly. And if you spend enough time on this forum, you'll likely turn into one of us (which might not be a good thing ), and purchase multiple sets of headphones for different applications and genres of music.
The only thing I'll suggest is if you are going to pick the DT 770 pro's, go for the 80ohm version. Beyerdynamic lists these to be used with portable devices, so they'll be easier to drive, and do not require an amp (although one might help). For me, a huge factor in portability is size and convienience. If I had to lug around an amp and constantly remember to charge it, I'd get annoyed with that setup pretty quickly.
Recently, I've decided to leave all my headphones at home, and just use decent quality IEM's for on the go daily use. For traveling though, I take my DT 770 Pro-80's with me. Have fun figuring it all out.
Edited by Bee inthe Attic - 3/28/12 at 1:18pm