I'd go with the STF-1. They're both renowned for how good they are with music. However, any sub with a -3 dB point above 30 hz, isn't worth much more than $500. Since they're both good with music, go for the STF-1.

You could get a B-stock HSU STF-3(read: huge ) for $480 - $505, shipped. This would be an awesome deal, I think.