I love my big green David Clark 10SH cans, especially for long marathon DX sessions. They're great in noisy environments, like my computer centre (since that's what they're designed for.) Bit on the bulky side, though, and they work best after a couple days' burn-in.
Barring that, Sony "Studio Monitor" MDR-V150 are also good DX cans. They have nowhere near the noise isolation the DCs have, but they're much smaller and (from experience, having had several pair over the years) have little to no burn-in. The V150 model was discontinued just over a year or so ago (replaced by the MDR-ZX100 model cyberdad mentioned) but they can still be found in abundance, since they were in production for nearly a decade, on Amazon or elsewhere fairly cheaply. They're also somewhat easy to service.