I recently went through a big Rat binge. I've found I like them for my "medium" gain stuff, which could likely be considered "heavy" gain for many, but probably not those here. If that makes sense. Anyway, after a lot of noodling and jamming to the songs I've been learning, I've found that my favorite Rats thus far - and in this order - are:
Dunwich Volt Thrower
Earthbound Audio Iron Pig (at 18v)
Frost Giant Bass Mountain
Fuzzrocious Cat Tail (diode options, but nothing else)
Idiotbox Blower Bass (standard version, though the new deluxe is tempting!)
Still want to try a Broughton Locust Star some time, but they're a bit pricey for me. Same for the MXR Bass Distortion, though that's certainly more affordable. Anyway, if you look back in this thread the past few months, you can probably see my posts, or I'm happy to answer questions.
In other bass news, to quote @Kaa - I got nothin'. Been too busy to play much the past few weeks. Need to get back to it and learn more stuff.
Glad I popped in here, was trying to decide between Bass Mountain and the MXR Bass Distortion. I love the other Frost Giant pedals I have, but I also saw that Steve from Imperial Triumphant uses the MXR and I dig his tone a lot. Guess it's back to research!