I preferred the Mad Dog Pro to the regular Mad Dog. Can't really pinpoint why. 

MD Pro does use the new baffle, so that probably brings some improvements to the table. But regular MD is a good deal too at $300. Treble can be a bit rough and peaky despite overall dark nature, but not bad overall (maybe Pro is better in this regard?). I still keep mine around for a reason.

399

I'll second the Mad Dogs, although I haven't heard them in a while. A respectable dark sound from what I remember.

Nominating two:
 

• AKG K7XX: less wonky than Q701, not lean and cold like K701. Not perfect, but at $200 a fantastic alternative to HD600 doing some things better and others things worse.
• Mad Dogs: dark tonality akin to Audezes, but price isn't bad at all.

Add the AKG K500/501 if you want an alternative to the AKG K7XX-series. They are not as plentiful as a few years back.