I'm currently using a Zvex Woolly Mammoth and a EHX Little Big muff. Both are highly rated fuzz pedals for bass, but are very different sounding. The Mammoth sounds tighter and has more aggressive tone in the high frequencies. Because its has a gate function, its possible to eliminate playing dynamics and just have fuzz or nothing. The LB muff sounds 'bigger' and more organic, unlike the buzzsaw tone of the Mammoth. I use both pedals separately to cover songs like Hysteria, Time is Running Out, Somebody Told Me, Song 2, Come as you are, Shout etc...
I also recently got a Prunes and Custard from JudeWee. Very nice pedal, and fuzz-like. To my ears its pretty much like a distortion + filter in-one. Very dirty and funky!
I'd recommend the LB muff like the others before me. Its the best value for that sound you'd probably want.