i use an EH Metal muff w/ top boost - great sound, full eq so no bass loss.
MXR DI+ distortion - chunky and ballsy!
Boss HM2 - Great fuzz sound and tons of low end boost with the eq.
MXR distortion III - mid gain grindy type sound. no bass loss.
Tone factor Fuzz saw - huge ballsy fuzz, no bass loss
MXR Blowtorch - Full eq + blend. great sounds all the way from light grit to full on muse- esque fuzz
Hartke VXL valve dynamic switch! - great chunky sound, again from light grit to full on distortion
My requirements are no loss on the bottom and must work well with my weeping demon to give solid scream type effects!
I've tried many more than this, but was left feeling wanting!
Previous tries - Marshall Guv'nor (bass loss), Most Boss OD/ Dist (just not 'right'), nano muff, pocket metal muff, micro metal muff, PD7 (great pedal, just not right for what i wanted from it) to name but a few!