Death by Audio Absolute Destruction - Fuzz

Used for noise music so cant vouch for is use on guitar. Works great for destroying samples though. I use it in parallel with another effects loop which gives great dynamics and variety. Can be tricky to dial in the settings where you want but once you do its a unique and impressive sound. Love using the sliders, very tactile and responsive.

It really delivers what its name suggests: it can completely destroy the signal and take the guitar into very interesting noise territories.
Beware: it easily gets out of control. Expect feedback and hisses and in general a bit of unpredictable behaviour.
It's easy to work with the sliders, however I think I'd still prefer knobs.