Again, so subjective, but my .02 are as follows:
I personally find the sound of the bike to be an integral part of the experience and I find the stock system to be lacking in this area. I bought a motorcycle, not a vacuum, it should sound like one.
I bought my bike with 200 miles on it and the previous owner had already installed a Staintune. While I like the factory-quality fit and finish, I would not pay that $$ for a slip on as the performance difference is negligible. I'm eventually planning to swap my Staintune for a full system (probably Pipemasters 4:4), but for the money I'd look at these 2:
K-Factory CSR Full system @ ~$643 USD:
http://www.samurider.com/?p=9151
It eliminates the stock catalytic converter and utilizes larger diameter tubing, so probably your best bet for maximum gains for your $$. Remove the sticker and it basically looks like an old Kerker, so it fits well with the period aesthetic. Multiple baffles are available so you can tailor the noise level to your liking.
If you prefer the stainless look, I'd go with the Moriwaki 1-piece @ ~$863:
http://www.samurider.com/?p=6448
Moriwaki is Honda's official aftermarket partner, so I would expect build quality to be quite high. Also kills the cat.
To get the maximum bang for your buck, you'd want to send your ECU to Don Guhl to re-map your A/F ratios and remove factory timing retardation - that's another $375 (edited). Again, K-Factory + Guhl ECU puts you just north of $1,000 = +~10 HP and SOUND!
grover