I always liked the stock wing, as I think it was influenced by the back of the Porsche 959. These days, however, every car has a spoiler, and something more agressive is nicer. As a pupil of the MYNSX school of car design, the golden rule is "balance is key".
The new NSX-R has lower side sills than the '01 model, and the slightly raised wing gives the car a certain balance that the stock model seems to lack. When I added my WW kit, I left the stock wing on for a week, but it didn't look right anymore. I then added the Comptech Aggressor and I have grown to like it more each day. I'm not crazy about the way it looks from the front, but from the side and back it looks factory.
I purchased the Burn-Up wing, but found that it would make my car look a bit top-heavy and didn't install it. Had I gone with more aggressive side sills, it would have balanced out the design. I think a lot depends on what other body mods you plan to incorporate, and the width of the wheels you have.
With stock bodywork or a WW kit, I think the NSX-R (OEM or copy) wing is the nicest, followed by the Comptech. If your car is wider on the bottom, you can go with something bigger and wider like the Burn-Up or one of the tall aluminum/carbon-fiber wings that are available.
Now, weather you should paint your wing black, body color, or get carbon-fiber is another matter.
