I have:
1. Sennheiser HD580s; my first decent headphones bought about 10 years ago, but sadly now relegated to the loft as they go through cables way too quickly and at £25 a pop I decided some time ago that I couldn't afford to maintain them
Still, got them for £60 new so can't complain too much
2. Beyer DT880s; bought these to replace the flaky Sennheisers and I immediately found them better. Probably my main 'hi-fi' headphones in use more or less every day. Excellent clarity throughout the range, good soundstage, great depth to the sound and they have that lovely transparency that good open cans give you. I really rate these.
3. Puretone Micro Monitor 3 (custom-moulded IEMs - see
here); I use these for my music work as on-stage IEMs but they are also rather good for enjoying music when commuting. VERY sensitive and so slightly tricky to drive without having the volume knob at like 0.5%. They really benefit from a good headphone amp but finding one with sufficient attenuation is really tough, so I tend to use mixer outputs which have multiple level controls
4. Koss KSC75; just got these for a throwaway portableish pair of 'phones to try. Initial impressions are good - really wide soundstage, good upper-mids, decent clarity, though I find the bass a bit poorly-defined and the whole range could do with more 'depth'. Having said that, for £15 I doubt I'd find better!
arty