It depends...
It all depends on what you're gonna use them for.
Tracking:
Any cheap closed phone that doesn't leak is gonna do it, because all that matters is isolation
Monitoring certain areas of the spectrum, using phones as microscopes:
- Sony 7506 is about the best "highlighter" I know. Doesn't sound balanced or good at all, but points out low-bass and digital noise very well. Most engineers I know check their mixes on these. They're the NS-10 of headphones.
- Sony 7509 isn't half bad either, flatter response than the 7506, but less highlighting effect.
- Senn HD280 needs a lot of burn-in time (more than 200 hours) to sound right. Bass is very deep, but it's really hard to judge the impact.
Mixing/Mastering:
If you plan on mixing/mastering with phones, I suggest high quality headphones that are relatively flat and diffuse-field equalized, which means open headphones in the vein of
the Sennheiser HD600, AKG K240DF,
AKG K501,
Sennheiser HD595, Stax electrostatics,
BeyerDynamic DT-880, etc. I use the HD600 and get very good results (to my taste at least).You need an headphone amp to get the most of those though.
Don't listen to anyone that tells you you can't mix with headphones. This is only true if you don't listen to music in headphones all the time. I never listen to speakers cause they all sound like shite to me compared to good open headphones. Since I only listen to music on headphones, mixing is easy. Headphones also take the room out of the equation (which means less $$$ spent) and they provide a much better sense of bass than nearfields/mid-fields. And don't even get me started about the hassle of having a room treated for a sub...LOL! Headphone are a low-cost excellent solution. The only speakers I can handle now are some B&W Nautilus in a treated room, everything else sounds muddy and fake.
TheDewd