Fuzz is an underrated thing in the guitar world unfortunately. People try a modern day big muff and make up their mind based on that alone, but there are so many types of fuzz. Typically (and I'm paraphrasing this statement) there are only three different types of fuzz, and hundreds of variations.
There's the Big Muff style fuzz, which gets its fuzz from cascading clipping stages and mid scooped tonality from a unique circuit which leaves the low end untouched while the rest of the tone gets squashed and distorted. There are also what called feedback caps on the gain stages which prevent the sound from becoming too harsh and bright sounding, lots of designs have them, but the Muff's are much larger than most designs. The modern day BMP is nothing like the older models, but luck is in sight because they're easier than
π to modify back to an earlier version. Pun intended of course. Lots of tweaking is possible with these circuits as far as gain, amount of compression, amount of mid scoop etc, but don't try to make it something that it's not, you will be disappointed.
There's the Fuzz Face style fuzz, which gets its fuzz from transistor stages only, no diodes whatsoever. The circuit gets its distortion from the way the transistors are biased as well as utilizing a unique feedback system which stops the fuzz from becoming 'harsh' sounding. The warm tonality it is known for actually comes mostly from its extremely low input impedance compared to lots of other pedals. Then there's the Vox Tonebender, which is like a much brighter version of the Fuzz Face.
There is the Univox Super Fuzz which couples a fairly typical amplifier circuit with an octave generator circuit to get an otherworldly kind of fuzz sound. The octave generator, when tuned properly via an internal trimpot, interacts with your guitar and amp and the sound is really like nothing else. There is a switch on these units which activates a mid scoop circuit for extra versatility. When played into an already crunchy and LOUD amp, the resulting tone sounds like the walls are going to come down. It's intense.
There's lots to do with fuzz and they all sound good to me