I have owned both and messed with both in a few rooms. If you are looking for value vs output go with SVS. If you are looking for sound quality and tunability go Axiom. Honestly, I would just buy an Axiom EP500 and never look back. Holy cow do they rock for what they are. But I am biased and push them on virtually all my installs. Owners are never let down though. Usually get a "holy shit" out of them. Then grins.

If you do go with Axiom be sure to order with rubber feet and place on carpet. I can make Axiom subs make bad noises on hardwood floors or spiked through carpet at low frequencies and high spl. There is a sympathetic frequency that causes a hammering effect and the floor to rubber feet interface being somewhat springy like carpet cancels this issue. Tip from the trenches. I don't blame the subs... High spl at low freq= kinetic energy.