HE-6 for most music listening. MB Quart QP-95X when the weight of the HE-6 gets to me. They don't sound a lot alike but the 95X is incredibly light and satisfyingly neutral in sound quality.
SRH-840 when working in somebody else's office.
HD25-1 II when traveling.
MB Quart QP-160 for almost all non-music listening, which includes watching random videos on YouTube. I have the computer set up to route iTunes to the stereo and all other sound sources to the QP-160. They sound good enough out of the computer's headphone jack and are forgiving of poor audio quality without muddying the sound. They're small and lighter than the 95X.
K240 Sextetts when I am in the mood for 'em. They are fun.