are you looking to replace it, or supplement it with something else?
if it's replace, i'd say grab a Jekyll & Hyde or the VS-XO. the XO can get pretty heavy if you tweak it right- the J&H can get super heavy on it's own.
if you're looking to supplement it the Box of Rock would be a good choice. Another overlooked option would be the T1M Punch Drive (right hand side of the T1M Pearl)- can get really ballsy gain-wise, and at $125 it's a steal. Another even cheaper option would be an EHX Glove OD, i've heard great things about that one
VS-XO is a good bet. There's a whole lot of sounds in that pedal and it's hard to make it sound bad. The left channel has a LOT of gain on tap too (it's eq'd more flat, not ts like)
What kind of drive are you looking for, something with mids or without mids? Not that I'm pushing you get a rat, cuz I know you said not to suggest that but I've got an 85 White face reissue rat and I stack it with my vs-xo... all I can say is, it really gets that gritty "rock & roll" sound on.
I run a Guild Blues 90 into a Fender HRDLX, clean side only. I use a Fulltone Fulldrive 2 for my main overdrive, and am actually currently looking for that "harder clipping overdrive myself" for the next gain stage. It depends on what you want to sound like, what kind of guitar you have, and what style you play. For me, I only play rhythm guitar in church, so I just wanted something crunchy that will sound good with chords and an occasional lead (if I ever learn to solo). Out of the pedals I've tried so far for that second stage harder clipping gain, my favorite has been the BMF Great Wide Open distortion. It sounds really really great at lower gain settings, and it doesn't color your sound. I had a Box of Rock but never used it. I didn't like it precisely because it was a "Marshall amp in a box," even though that's what it was marketed as. It was way too dark and boomy for me. I decided I wanted something cleaner, more transparent, so I'm working on selling the BOR right now. If you want to sound like you're playing through a cranked Marshall JTM, the BOR is perfect for that. But I wanted my amp and guitar to actually sound like my amp and guitar. I have a few more that I'm going to try, but I have a feeling as of right now I'm going to wind up with the BMF.
I was looking for something like you described as well. I couldn't ever find exactly what I wanted, so I had to make my own. I modded a black Russian Big Muff by replacing the first pair of clipping diodes with LED's. This cleaned up the Muff so it wasn't so fuzzy. Then I took the diodes that I removed from the first clipping stage and added them to one of the diodes (in series) in the second stage, so the second stage had one diode facing one direction and three diodes facing the other. This gave it a really raw asymmetrical ripping distortion sound that I haven't heard anywhere else. Lastly, I added a mid control and a 9v power adapter. All in all, they were really easy mods to do, assuming you know how to solder.