A little history also courtesy of Josh of JHS pedals (he's not trying to sell you any of his gear either, He is cool like that, He shall mod almost anything you may ever want mind, as well as his own pedals, being really damned good I have found with the few that I have bought.
Personally I'm a Boss FZ-2 Hyper Fuzz and IC Big Muff type of guy when it comes to fuzzes, I do not like typical old/classic style fuzz, It is all about being able to nail EyeHateGod and Electric Wizard (Dopethrone-era especially) sounds so I don't have that many fuzz pedals.
I have an old EHX Russian-made Big Muff which I only bought as it was the cheapest available at the time (the late '90s) and I still hadn't got my needs/wants down as I was learning still, Had practically zero budget, So I still have that and it is good for a silicon-based transistor fuzz, It has a nastier, more aggressive sound to it with everything fully maxed out than any of the typical American made Big Muff's that I have played/tried/tracked over the years.
Have an old MXR "Jimi Hendrix Fuzz System" which is an octave fuzz, I don't use it conventionally though, Instead of using the built-in fuzz I put any number of high-gain distortions before it and that feeds through enough to catch the Octavia/Octavio foldback part of circuit whilst not getting too fuzzy, Really vile and one-note glorious riffage are instantly there. I can't recommend as MXR stopped making this one many years ago, when I do add some of the fuzz onto what is already a ton of filth, Get some of the evilest gated octave fuzz, I'd love it if this were re-issued.
The Boss FZ-2 Hyper Fuzz is my goto fuzz and well it is a distinct box of hell that can be unleashed in two modes along with an odd clean boost with the EQ/tonestack available as a strange but semi-useful bonus. Behringer's cheap line of pedals have practically a like for like clone of the Hyper Fuzz which can be had for like £15 to £20, Sometimes less than that. I have a few after grabbing one just to try against my original and yeah put in a new enclosure can handle any abuse which is the area the Behringer enclosures on that range are cheap plastic, So not suitable for live use, For the money though vs buying a used one, Well worth it IMextremelyHumbleHO. It's not the pedal for getting a Rolling Stones, Led Zeppelin, Hendrix or even any of the fuzz heavy grunge bands such as Mudhoney, You can get Earth-type wrongness from it though!
Electro Harmonix IC Big Muff, The fuzz that is required for nailing the Smashing Pumpkins fuzz/distortion sounds, It was by accident that they ended up with the IC-based big muff fuzz pedals, They got them as they were cheap due to not being wanted at the time, EHX only did a rather short run of this variety, ITo me it is a fuzz but with the control that you can get from distortion but can easily be pushed into unruly, very over the top areas also, I like the clarity and note definition that as said is quite like being in between a gain-heavy fuzz and a modern, british-style high-gain distortion due to pronounced mid-range, They have been re-issued and at a really great price too.
Electro Harmonix Octavix, I got this one a few years ago as a gift which was cool since I rarely get anything audio gear-wise bought for me! This one is good for more classic fuzz sounds along with having the Octavia/Octavio circuit built-in which enables that awesome octave up foldback sound, Since I got gifted this, I have used it where I would usually always reach for that old MXR JH Fuzz System which it is along the lines of/very close to. I do not use the fuzz part much, So I can't really give a meaningful overview of it, It works and nails what I want/need just fine.
For something built to very high-quality standards, Roger Mayer's Octavia Classic is likely going to be of interest for anyone wanting an Octave Fuz, IIRC they are around £240 new:
FullTone's pedals are always good quality and their Octafuzz is another ideal place to look, It is also quite a lot less than Roger Mayer's octave fuzz boxes:
For more wild offerings of doom, The names which vurt has mentioned are certainly not at all going to disappoint.
Earthquaker Devices, Anasounds (Crankled Bitoun Dual Octave Fuzz a great example), Bearfoot FX, Beetronics (Octahive, The octave circuit can be switch on and off on this via a toggle), Caroline Guitar Company, Death By Audio, Z-VEX..etc. etc. The OCTAVE FUZZ is your oyster in the world of the smaller name builders, Some that have what is a cult-like following except without the creepy parts
Hope there is something in there that might help get you somewhere close to what you are looking for. Each circuit behaves differently often times as in you will probably want to try a selection out before buying, Same goes for what you are feeding into it and the amplifier or amp simulator...etc. as they are shapeshifting in quality at rather high decibels and SPLs through a cranked valve and also the good quality transistor/solid-state analogue amplifiers which don't translate going into the box and a modelling amps. Obviously neither is superior, Just can be very different results-wise due to the signal chain and what it is interacting with.
All the very best, Seasons greetings.
Sorry, I haven't been around for quite a good number of years John my friend, I do hope that you are well and things are treating yourself and your's good. Life man and all, been a bit rough, Still is but I am working to getting back on teh social media, To Ketchup and stuff. I have missed good company including yourself and others, It has been total hermit life. \m/