I've owned a few green muffs (3), a few more black muffs (5), Little Big Muff, a Fuzzrocious Green Stache, Wren & Cuff Pickle Pie B (the one that Grygryx reviewed on BassFuzz.com), an Earthbound Audio Supercollider (with Mid Switch), a Blackout Effectors Musket V2 and got a chance to A/B the Musket with a Earthquaker Devices Hoof Fuzz, I've also tried a Bass Big Muff.
Other muff-like fuzzes i've owned/Tried (ie: they're not muff circits but sound alot like muffs:
Colorsound Tonebender
Colorsound Bass Fuzz - based on a Jumbo Tone Bender
Myrtyl Pedals Corvid Fuzz (with Flat Mids) - bassed on a Supa Tonebender
SFX Micro Fuzz (very similar to the Colorsound Bass Fuzz, but with higher quality components, Much Much smaller, 9v input)
Electronix (now Ziebek) MessDrive Hybrid+
Of ehx muffs i've tried - the Green wins all, just seems fatter and creamier and more natural on bass, the Black is a little tighter and refined - still creamy and keeps the lows with the tone down (the green has more useable bass tones higher up the Tone control).
Didnt get on with the Little big Muff that much - the Bass Big muff was great, but I didnt feel that it sounded as 'special' as the russians.
The Wren & Cuff PPb had an amazing grind to it and is very versatile with the filter and clean blend.
The Fuzzrocious Green Stache just sounded great - it wasnt hard finding a great muff sound.
The Colorsound Tonebender sounded great for Stoner Rock-type tones and kept the bass really well - but its not great for crunchier more harmonic-filled sounds. Like the colorsound bass fuzz, the tone control keeps the bass intact quite far along its range, more so than a muff.
The Colorsound Bass Fuzz and SFX Micro Fuzz have a large mid scoop which actually makes the sound of the pedal - the low end is MASSIVE - I had the tone control at 3 o'clock and still got tonnes of bass and treble - i've not seens another fuzz that will keep that much bass in the signal without a clean blend. Also has a great synth-like sound with the gain up.
The supercollider gets alot of love round here but I didnt love it as much - just a personal preference - Its possible that I would have prefered the version with the mid-control, rather than that mid switch.
The Musket is pretty great - very versatile with its mid cntrl and PreGain control - I had it applied to the high end of my signal (via a SFX X&M Crossover Mixer) for a great biting distortion that loves to feedback - the Musket (unblended) also won out with my A/B with the Hoof Fuzz - it just sounded thicker and nicer to me.