I will say one thing from my experience and that is all I will do.
It's all about the install. Before, I had two 12s and didn't get very loud and I thought the subs were junk and thought I needed bigger and better subs. In a stroke of luck, I won a free sub from fi audio, so I had to build a box for it. For some reason, the one 12 sounded louder than the two other 12s. (which imo were of about equal quality) and provided more than enough output of my listening needs. In sum, my reccomendation is to throw that box out in the street. Search 'free ported subwoofer box plans' there is a program that you input the specs of the sub, build the box, and presto. It will sound pretty good, get the output you need, etc. It isn't about the best sub. It is about the install. I could have a $1000 sub, and some on this forum could make a sony explode sound better than me.
Rather than concentrating on this sub or that sub, determine you application (both wants and needs) and determine what type of box would best fill those needs, and then from there determine what types of subs work best in that box. It is a process, it is not throwing some random *** box in your car with random as subs and hoping for the best.