My only gripe with a white background is that the smallest bit of film algae and/or diatoms are VERY visible. Granted, probably won't be an issue beyond 4-6 months once your system settles in, but occasional blooms quickly become an eyesore if/when you get them.
I have a mostly white background on my planted setup because it helped reflect light into the back corners of the tank...but cleaning the back glass regularly got old, so I went with black instead and haven't cleaned the back wall since.