Re: Electro Harmonix Muff
The Double Muff is an overdrive pedal, the other two are fuzz boxes.
The black and green Russian Big Muffs tend to have a little more bass, but are even more inconsistent in build quality than the NYCs....so make sure you play a bunch and choose the one you think sounds the best.
Just a word of warning though....Big Muffs only have one sound to them....so make sure you like it before you buy it.