Well to be absolutely frank, thats the most vague question you could have possibly asked. Here are some things that will help us help you (your friend):
What type of music does your friend listen to?
Will your friend be using them at home, as portables, or both?
What will they be playing the headphones through? (iPod, Computer, Stereo Reciever, ....i'm assuming they dont have a dedicated headphone amp)
Do they want something "stylish"? (to most of us this is unimportant, but some do care what their music "looks like")
Most importantly, What would they do-oo-oo for a Klondike bar?