Would a tennis ball have more volume than a golf ball?

On first analysis, the Basketball would appear to have the higher ratio (regardless of units of measure due to its larger size).

But the situation could be interpreted as being rather more complicated than that. The tennis ball is thoroughly covered in very fine fibers, and the basketball has a surface that is dimpled. Both surfaces increase the surface area of their respective objects, but the high aspect ratio fibers of the tennis ball are massively more significant in this effect.

Thus, when considering the actual surfaces, the correct answer would appear to be the tennis ball, by a fairly large margin.