I think you'll find that, in general/roughly speaking, 3/4 is the more commonly used size (and of course, the size of basses was never standardized, so there are smaller and larger 3/4's, likewise for 7/8 size basses and I imagine 5/8 size).
That's about all I can say. The rest and plenty more information on bass sizes and much, much more can be found
here.