1. Sony MDR-CD900ST's.
Still the reigning king of the mid range. Don't think anything is going to be topping them anytime soon.
2. Sony MDR-7509
Just got these yesterday, and have really been enjoying my time with them. Pretty warm sounding overall, though some of the treble frequencies are a little boosted, and the upward extension is good. Soundstage is really huge for a closed headphone, makes them really awesome for movies and games. At first the mids on these sounded a little recessed, but they're just lacking that upper mid-range bump. They're more focused on the lower mid range, which suits female vocals very well.
3. Sony MDR-ZX700
A little bright in the upper-mids and highs. Kind of remind me a little bit of a Grado. I find myself needing to turn the volume down to prevent myself from getting fatigued, but once I do that, I find plenty to like about these. The soundstage in particular has me impressed. The forward projection of the sound has more depth than the other two headphones I own. I would have figured these would be better for small acoustic arrangements, but I find myself preferring just regular ol' mid-size band arrangements. More than anything though, these have me very interested in the Z1000's.
Oh, one thing that really, really bugs me about the ZX700's is I can't use them with my Little Dot I+. They are very, very, very noisy out of it. I have no idea why it's so noisy, and it bugs the hell out of me.