Re: which one.
I would go with the W7's sealed. Gives you a nice low end (no steep roll off) and smooth response through the range. Should get pretty beastly with enough power. I've always liked how clean JL's sound. I've demo'd W6's and W7's side by side (local car audio shop) and couldn't tell a huge difference on only 500W RMS.
'65 VW Bus
(2) PG Ti 12's, (2) Aura Sound 8's, (2) SoundStream 6.5 coax, (2) Alpine Type-S 6x9's [rear fill], MBQ DSC1500.1D, RF 501X
'02 BMW 330xi (AWD coupe)
Harman/Kardon 12-speaker System Option - sounds good =)