Help deciding on a SUBWOOFER ?

I want to get a subwoofer but cant decide on which one. ALL I CARE ABOUT IS SOUND QUALITY. Im was looking in to JL Audio and was looking at the 10W6v2 for $280 and the 10W3v3-4 for $160. But is the 10W6v2 REALLY WORTH $120 MORE? and how about that JL AUDIO 8W7 for $250 is that even better than the 10w6v2? And how about ALPINE their prices are ALOT better. I was looking at their type r's and for the most part people said their sound amazing but then i read 2 reviews that said they kinda sound a little muddy? but do you think the 10W3v3-4 for around the same price would be better then the type r.? Now as for the amplifiers, I want to get the most BANG FOR MY BUCK in QUALITY. I was looking at the Alpine MRP-M450 or Alpine MRP-M500 for amps. i mean can you really notice the diff from a alpine amp and a jl amp A $150 DOLLAR DIFFERENCE? maybe you can point out a diff AMP?