How much are you willing to spend?
For the budget class, the clear leaders (in my book) are the Sennheiser HD-497s. These, for about $50-60 USD are pretty capable, and they sound much clearer than their HD-500's which retail for 1.5x the price. Some also think that the Grados in that price range are good, but they are too harsh for me until you move up really high in their lines. Up at about $80-100, if you are able to find the old Sony MDR-V6, they are an incredible find. Be sure it's a V6, not a V600, though. The V600 is a disgrace (again, in my opinion), and many people often mistakingly call the V6 lacking in bass and treble because they are really referring to the 600. The bass clarity and tightness in these headphones beats that of any I've heard before. It's all boring from then on up until you hit around $350, at which point you can get the Etymotic Research ER-4s (don't go for the p or b models, though). These are generally regarded as one of the top 5 headphones, regardless of price (#1 being the impossible to find $12k Sennheiser Orpheus).
Hope this helps.. If you give us a budget range, we could probably help a bit more
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