sub woofer dilemma, help

I have a pair of Alon II speakers and would like to add a sub woofer to my system. I am running off of a B&K ST202 with a B&K Pro10MC. I am looking at Velodyne models ULD-15, F1500/F1200 or FSR15. Of these, which would be the best musical match?
The ULD-15. Next would be the FSR15. I wouldn't consider the two F-series mentioned.
Good luck!
I found the Boston PV1000 to be a clone of the similar Vel, and far better than the F-series, too. Great value, and VERY fast, mating with my Spendor front trio magnificently.
James. EMB-1000 or EMB-1200 (new).
Art of Sound or REL. Something that connects to your speaker taps will give you the best blend.