I apologize for bump the old topic, but I have some interesting observations that I would like to share, maybe this will help someone in the future because once I was on the lookout for useful advice.
Two completely different woofers with completely different objectives.
It depends on what music you listen to, space, power you will be putting to it. Just a bunch of variables. If you like a Musical sub that will still pound the W6 is for you. If you like a sub that will hammer but lack in some of the musicality the L7 is for you. I have two L7 12's under my dash and they pound!
The JL is an exercise in balance and precision. It's linear, fast, low distortion, deep, and does these things with minimum moving mass. Great musicality and it will hammer.
The Kicker is pushing around a lot of moving mass with more of a single-minded focus. It's an absolute jackhammer but not very articulate.
I have a 12" L7 with the KX1200 https://atfulldrive.com/best-car-subwoofer
running it and it absolutely slams but as other's point out, it's not the same SQ as the JL. Do you want boat shaking bass(L7) or do you want a sub that hits hard on the dubstep but also adds some deep tones to country (W6)? I personally like the rip your head off bass but on some songs, you can tell that it's not the best choice of sub for that particular song.
There are a lot of useful videos on this subject on Youtube, I'll leave one here, Hope this helps someone. Good luck!https://www.youtube.com/watch?v=mYZ-ZTa_BcA