In my Audio technica collection i have the AD700's, M50's and a pair of ATH-ES7. And to be honest I'm happy with all of them. However each excel in a different area.
AD700 - These do lack a lot of bass and are open so you need a quiet space, If your into techno or metal steer clear of these. I only use these for chilling on my beanbag listening to acoustic and classical tracks... the high end and sound stage is almost orgasmic (for this price range). They aren't cheap feeling but they get older they do "creek" if you move (because of the plastic wings).
M50 - I use these at work, they are good all rounders.. and out of all three they have best all round sound reproduction... Probably a little to big for the bus but are extremely well finished. All the senhiser people at work have conceded these are the shiznit.
ES7 - Beautiful looking headphones that literally do turn heads in public.. They sound very similar to the M50s in a more compact housing, because of the size the M50's have a little more depth. But these rock out in a public environment. Oh and the cord is a little cheep with these (in connects to both cans which is a bit crap for a headphone in this price range)
Summary -Which are my favorites? I would say hands down the AD700's. But if you asked me "which pair most are the best value and people would like?" I would have to steer towards the M50's. As the AD700's excel in only one area.... My beanbag :)
Oh as this is my first post just so you guys know. I'm a 30 something web developer who deals with a crap tone of audio editing
If you read the replies, I actually ended up going with the Fischer Audio FA-011 from their masterseries. They are basically a very much improved version of the M50s with a great soundstage. I will contend that the AD700 is just UNBELIEVABLE for acoustic and classical, can't beat em. For my next acquisition I'm looking towards mr. speakers Mad Dog. It is a modified fostex T50RP and is supposed to be better than an lcd2 and almost comparable with an lcd3!