ilovefuzz.com

I like it. It's a bit boomy but apart from that it's pretty neat. Sounds way more like a real Muff than the Little Big Muff I tried.

I think a fuzz face derivative would work well.
They tend to be more EQ-neutral.

Also a dirty boost slamming the front of your amp is a good compromise between amp dirt and a fuzz.
Creepy Fingers Doomidrive gets me there. I often just leave that on and play with my volume knob.