I love my PB 13 Ultra and the specs and reveiws of the PB12 plus with the new Sledge amps are very good, I wouldn't hesitate to go with another SVS if I ever have the need.
I keep hearing good things about Funky Waves as well.

http://www.funkywaves.net/catalog.cfm?item=fw12_x

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70