I have both the Sony MDR-V6 and the Audio-Technica ATH-M40fs. The Sony's are "fun" to listen to music with but the Audio-Technica's are great for knowing (monitoring) what the signal really sounds like.
BSW has a great price on the ATH-M40fs:
http://www.bswusa.com/prod_item.asp?item=ATHM40FSHard to beat for the money! I agree that Beyer and others have super headphones, but for less than a single pair I bought the Sony and the Audio-Technica.
And I tend to agree with some others here, the AKG's don't do much for me. They are studio standards, but the top-end sounds very subdued to me.
Ivan