2x10 vs 1x15

So, like any good GenX player, I've had pretty much every possible amp combo possible, from SVT's to Peavey's to SWR's to Edens and so on and so on. If you were looking for a cab - SMALL cab - and it was being powered by a 50W tube head - would you want a 2x10 or a 1x15? Why? And don't cheat say...