I vote for the 2 10W6 subs. the W6 series has a much wider REAL frequency response. The W7 series is best for very low end bass (between 20-50Hz). The W6 series is perfect for filling the gap between low end (say 30 Hz-250Hz) to the midrange speakers.
Having 2 Jlw6 subs will allow you to have fuller bass because you can move more air while playing at a lower volume (cleaner bass IMO) plus it just looks cool.
My reccomendation would be to get a dual 10" sub box from here:
While the subthump box only offers .49 CuFt of airspace per sub, using polyfill in the box will provide the acoustic illusion of a larger box. JL website reccomends .625 CuFt of space per sub and with polyfill or fiberfill you can simulate somthing along those lines.