I'm kind of shocked at myself, but I think I may almost be turning into a passive guy...
I grew up playing an Alembic, active Yamahas and various flavors of Bartolini-powered actives. I LOVED that Bart round low-mid thing. But I got sick of that defined-yet-muffled-in-the-mix tone. Which is similar to what I hear with MTDs and the like. I like my Bongo, but its tone is pretty far from warm.
I now play an NYC Sadowsky 5, which is of course famous for its great preamp. I almost always play it in passive mode. I would like the tone shaping, but something in the mids is lost in active mode. The Sadowsky pre has no "flat" setting. It is boost-only, and with bass and treble all the way down, it is still a bit scooped. I like mids, and in general the mids in a good passive seem a bit more complex, especially in the attack portion of the note.