I have used many headphones in my life as a recording engineer and the best deal out there right now IMHO is the Audio Technica ATH-M50. Nice sounding, good isolation and nice bass. The Beyer Dynamic DT770s are also good, but much pricier. The Ultrasone 750 Pros are also very nice.
I use IEMs a lot these days and Future Sonic Atrios are nice sounding, they have a single driver but aren't a hearing aid armature type. That said, I usually use Westone UM2s. Both are excellent when it comes to low end response.
Everyone hears these things differently because of different ear construction, though, so YMMV considerably.
Edwin