My vote is white - and I've probably been responsible for the decimation of hundreds of 9 foot rolls between my careers as art director, creative director, and photographer.
I've always purchased arctic white, but have had no preference when stocks are low - I generally say "nine foot white seamless please". It doesn't matter much, the way the light falls off is what makes it happen.
White is pretty versatile in a decent sized studio. You can get a wide range of grays depending upon lighting and having some distance between the lights and the BG.