If you're going to strip it down to a bare chassis and repaint (which is what you should do if you plan on changing the color of the car for resale) then paint it factory purple. It's not an obnoxious color and it's very rare. You could also paint it factory gold but I don't know any TT's ever came in that color.
Otherwise if you're just asking regarding a respray then stick with the original color of the car.
"The 300ZX Turbo is a dance; it's a song; it's rolling, roaring automotive art. There is no color that doesn't suit it. There is no mood-lifting chemical substance it can't replace." - Automobile Magazine
