it's going to be a real toss up
I really like the SVS Plus 12 at $1350 well two of them.
maybe order one and one Axiom and compare.
HSU, seems to be great too lots of good reviews, however, by the time shipping and taxes, and brokerage and duty and the shipping again it is up there with the SVS.
and I am not sure I like a floor firing sub.
I was looking at the SVS 13 Ultra, but not sure about a sealed cabinet. Atleast with the SVS 12 plus I can seal it off if I want to.

Pioneer sc-1525
M80 HG Cherry