Some useful info here….
http://www.soundonsound.com/sos/jan10/articles/studioheadphones.htm
It’s generally accepted thay open backed (poorer isolation) sound better then closed backed (better isoation), so you may have to decide on where you want to comprimise.
I have HD595, HD650’s and Beyer DT880’s (all open backed) + some close backed sennheisers. I like the HD650’s best, but the DT880’s are really nice (bit more ‘hifi sounding’). If your using with an Ipod, don’t get high impeadance ones (my DT880’s are 250ohm, and an ipad struggles to drive them to acceptable levels, you can get 32ohm versions which would work better, or buy an external amp).
AKG 701/702’s are also highly regarded, but not heard them.