My money’s on Rat. He’s uglier, meaner and sneakier.
I know not this rat, but Bun-Bun has survived much and is always well armed. I’d go with Bun-Bun.
Man, it’s weird seeing something like this here instead of on the Sluggy boards.
Sluggy boards? There are Sluggy boards? More than one?
Rat had a nuke at one time. Worst thing I’ve seen Bun-Bun with was a bazooka, but I’m not up to date yet.
Moving this to Cafe Society, hoping to Ghod that the mods there don’t notice it and send it back. 
Oh, please! Rat isn’t even worthy to lick Bun-Bun’s fuzzy feet! While Rat has the snark and the unpleasant disposition, he’s definitely lacking in the almost casual ability to simply snik and stab. I’ve seen him bop folks on the head, and he regularly beats Pig up, but the general willingness to switch to murderous mayhem isn’t there. I just can’t see the cast of Pearls running away to go into hiding because they accidentally erased Rat’s Baywatch tapes.