I have 2 10" W3v2s and i love them great sq and they get really loud too. Although the L7s are known for nuthin but spl i would say the JL's would get louder because u would have so much surface area with 3 12s over just 2. not to mention the JL is just all around a better built and more dependable sub IMO.
Strictly for spl purpuses... box tuning, and so on. The L7's would win. Now, I'd rather go with the 3 JL's, better quality/reliability, and still will get loud! Surface area has some to do with spl, but theres a lot of other factors that go it to it as well. Xmax, box, car, just to list a few.