Do you have a dedicated amplifier, or just a portable player / standard computer soundcard? If the latter, then pretty much write the K601 off the list. Also, depending what rating that DT770 is (I don't know enough about the models to say), it may not sound good without a dedicated amplifier either. That leaves you with the D2000, and whilst I recall reading something that it'll work well without a dedicated amplifier, I don't really know anything about it, so don't take my word for it.
And "for all kind of music" doesn't help, because some of us here use either of them for all kinds of music. "Best" is also entirely subjective.
What headphones do you use currently. How do they sound, what don't you like about them, and what would you like to be different about them? Also, we need to know the purpose for these headphone. Will you be listening at home in a quiet area, or out on the move? How long do you tend to listen / wear the headphones in a single period (comfort even makes a difference). Without these kind of answers, no one can really give you any pointers.
