The GK isn't very fussy about cab's. I've run mine with Avatar, Music Man, SWR and Bag End. It sounded good through all of them. Personally if I were out looking for a new cab, the only things I would look at would be neo, lightweight cab's. As a single cab, the Avatar 410 is hard to beat for the money.
Two 2x10's is a nice modular setup. Take 1 for small rooms, 2 for large. Split them to each side for a little lower volume when you have FOH support. Stack 'em on end for better monitoring and fewer hot & cold spots than a typical 4x10 out front. So a pair of Avatar 2x10's - ones with the second generation neo drivers if you go used - would be a nice sounding and practical setup.
NOTE: in your OP, you mention 'cab powerful enough to handle ' not to be preachy but that's maybe not the right way to approach it ... You've got a powerful head. There aren't many cab's out there that you can dump that kind power into without smoking something. Those that are, are not real efficient in general. So watch that Woofer control (Master Volume) and listen to your rig as you bring it up - turning that beast all the way is a sure way to have your credit card smokin' as you order replacement drivers.