Go with the B&W 683's. They have better bass and a bigger and better sound than the 684's which are not really an improvement over the 685 bookshelfs. I listened to all three as well as the NHT Classic Three's which I really like.

The NHT's have a totally different sound than the B&W's. The Classic 3 has excellent bass and a warmer, smoother sound compared to the B&W's. The B&W's have better resolution and more prominent treble and sound a little brighter which some people take as sounding better. I find that after about 30 minutes this becomes fatiguing.

But it all boils down to what you personally prefer. If you go with the bookshelf's you will need to spend about $100-150 for a good pair of speaker stands.

Good luck!

As far as the sub goes, you may find that you don't need it with the NHT's.