You cannot go wrong with Sennheiser HD650 or AKG 702 (I have the latter, they're so good for checking mixes against monitors). Remember though that these are open format so if you're going to do recording, you'll need a closed pair of cans like MDR7506 - I'm not a fan of these for checking mixes but they're great for dubbing.
... and +1 on the need for monitors. Headphones - regardless of how good they are - should be intended to augment not replace monitors.
I | mUsIc