I mean, that its impossible to tell you how loud something can get, or what will sound better, Its all in the install, you could totally mess up the box and have it sound like crap either way...
I have 2 12w6v2's and 1 13w7. I like the w6's a lot more. I just use the w7 when I want spl. The w6's are sealed and the w7 is ported. Totally depends on what you are after. The w6's sound great, the w7 sounds pretty good too. Just depends if you want sq or sql. Very install dependent!!
Personal prefrence for me is I like the W6v2's over the W7s. Don't get me wrong the W7's sound nice, I just like how the W6v2s sound better. W6v2s are some of the better sounding subs around right now.