NHT Classic 12 vs. PSB Subsonic 6i

Need to upgrade sub for my family HT.(winter is coming, more movie watching). Two show similar specs. and cab. foot print
is favorable to us. One of these two or another choice?
As a newbie I am very much confused. Help!
I would also consider Hsu Research and SVS for similar foot print sized subs. They typically deliver more per dollar.
second the hsu, which is great value. i also really like definitive supercube for ht.