I have several. In order of use (starting with the most-used):
- Sennheiser HD-600 with new Cardas cable (new cable on the way)
- Sennheiser HD-600 with old Cardas cable (I have two sets of HD-600s)
- AKG K-340, about tied in use lately with....
- ....Grado HP-1 with JGSUWBR cable
- Sennheiser PX-100
- Sennheiser PXC-250
- Etymotic ER-4S
- Sennheiser PX-200
- Sony MDR-V6
The HD-600s I use in both my main rigs, and sometimes even portably, because, sonically, I haven't yet used another headphone in my rigs that sits better with me. Overall, the HD-600, more than any other headphone I've had in my rigs, gets me closer to the ambience, emotion and feeling of a live musical performance (particularly with jazz, classical and other acoustic music) than any other headphone I own. As such, I currently use the HD-600 far more than any of my other headphones.
The K-340 is a very interesting headphone, extremely enjoyable to listen to because of its very nice midrange-to-mid-treble detail, and a very large headstage. Fun stuff. Limited at either extreme? Yes, but a very fun, enjoyable, musical headphone, nevertheless.
I enjoy the Grado HP-1 very much, too. To my ears, it's more neutral, particularly through the mid- and upper-bass, than the HD-600; but the presentation is a bit too close for my preferences, and I don't find it to be as capable as the HD-600 in terms of a sense of spatial accuracy and presentation. I find, for example, that the soundstage benefits of upsampling are a little less evident for me with the HP-1 than with the HD-600. The HP-1 is a wonderful headphone, though, but just not my favorite -- I can understand why it is the favorite of many, it's just not mine.
The Etymotic ER-4S is, sonically, one of my favorites, but, with 25 dB to 30 dB of isolation from ambient noise, it's too isolating (for me) for general use. Nothing beats the ER-4S on a plane, though, when you want to drown out the din of the plane; but even then it's sometimes too isolating, especially if you're flying with someone you'll be talking to.
The Sennheiser PX-100 is currently my first choice for a portable headphone for its combination of impressive sonic performance (considering its size and price), durability (so far), portability, and open-backed design (I usually need to be able to hear what's going on around me -- phones ringing, people, etc.).
The Sennheiser PXC-250 is usually what I turn to first when I want more isolation than the PX-100 (or any of my other open headphones) provides, yet don't want to enter the isolation chamber that the ER-4S so effectively creates. It's probably the best-executed consumer-use active noise cancellation circuit I've used, and provides the most acceptable sonic performance with the noise cancellation activated than any other of this type of headphone I've tried. Still, the PX-100 sounds better to my ears, but, again, the PX-100 is very open. Because I have the PXC-250, I only use the PX-200 while exercising (which isn't often enough lately).
The MDR-V6, an old pal o'mine, sits largely unused (in fact, I think my older brother currently has them), because, with the other headphones, I just don't find myself turning to the V6 much at all anymore. I think I bought my first MDR-V6 back in 1985, so it'll always have a special place in the hobby with me.