Really depends on what your parameters are regarding volume, size, portability etc.. I use a Fender Rumble 100 combo at home and for the smallest gigs but it wouldn't manage alongside a proper drum kit. Maybe a 200 would do the job.
I couldn't get past stuff in different keys and trying to remember that if you saw a note it either had to be flat or sharp, sometimes a whole load of them in a given key. Way to complicated for my limited brain power. Then trying to get to grips with crotchets, quavers and all the rest of it convinced me I was only ever going to play by ear with a smattering of chord progression knowledge chucked in. I only started learning theory because I was in a band with a load of 'proper' musicians who seemed to be talking a whole different language to me and I didn't understand a word of it.
Does it crackle all of the time. One of my amps crackles a bit but if I adjust the master volume a smidge it stops doing it. Probably needs pots cleaning and a bit of a service.
Drum machines can be quite expensive. I reckon an old tumble drier with a couple of bricks, some pebbles and a handful of pea shingle would work for us.
You've reminded me, so thanks. A while back, in a fit of boredom, I bought a Green Russian. I have no idea why because to my mind, fuzz on bass is bloody awful noise. I'll be putting it in the F/S section soon as I get round to doing some pictures.
As you say, probably a lot to do with playing technique and style. I play pretty light with my fingers but quite hard if I slap, so consequently, I use a fair bit of compression. The Filter Twin absolutely loved this and produced some epic sounds.
I had the M82 and an Aguilar Filter Twin when I was playing the kind of stuff that needed an envelope filter. Out of the 2 I much preferred the Filter Twin because, as you say, I found the MXR a bit thin sounding. Just personal preference though. The M82 got shifted pretty quickly.