I play through a Boss GT-6, typicall using a Dual Recto model. Tonally, what I'm after is a combination of Helmet, Killswitch Engage, Unearth, and Meshuggah.
Basically, hella-gain, not really boosted or scooped mids, tight bass, and lots of clarity with a hint of mud 8)
I can state what I like and dislike about almost every Duncan and EMG, and many DiMarzios if that would help.