I use a 2x12 Avatar open back which, to me, sounds great, but I'm going after more cleans and more "vintage" type tones. I've used that cab on both my RK1 and my F-50. You may want to consider a 2x12 closed back cab. That would project a little more and give you more punch.
The Avatar cabs are a good value, sound great, and are well made. It will save you a good amount of money over some of the other name brand cabs.
I've also heard good things about the Genz Benz G-Flex cabs, although, have never had the chance to try one.