A lot would depend on how much power you have to hit them with. Not sure on specs of either sub, but 1 good 12 with the right box should bang pretty good.
what would hit harder and sound good at the same time, one 12 mmats dreadnaut or two 12 re audio sxx?
Absolutely true. I'm not real impressed with the re stuff anywho because a buddy of mine has 4 sxx15"s ported and another with 3 12"s ported and neither subs seamed to move a whole lot even with excess power, maybe it's their boxes just sayin. I know nothing about the mmats.
I like the mmats. As always, the enclosure will make a huge difference as well.