[JET]

Good quality 15's are by no means sloppy. I like nice tight bass, and they can deliver. I do prefer a 15 in a sealed enclosure though, it will keep it tighter. Cheap 15's give all the rest of the 15's a bad name though, you need a big ass magnet and VC to move that cone accurately.

If you are on more of a budget, then I wouldn't go Def Tech, they are nice but are spendy. Polk's are pretty nice, especially for the money. I would recommend buying a nice quality receiver, med high quality front and sub and med-low quality center and rears. You can always upgrade the rears and center later, but they play a smaller role in things.