rim backspacing

Running a stock width rear what backspacing is best for a 10" rim?

I wanted to run Pro-stars wich come in 6.5"

Drag-lites come in 7.5"

Or I can just get a set of AutoDrags like I have now with 7.25"

I really want a set of Aluma-stars but they more money then I want to spend on rims.