I am a beekeeper.
10 vs 8 depends on a few things
foundation or drawn comb?
In foundation we use 10. It gives less room or burr comb or "funky" comb to be produced. burr or funky comb make more if a mess and decrease production
once the comb has been drawn on the first year we drop to 9 in a box for eaiser manuvreing of the frames and better uncapping with the mechanical uncaper. But we make sure the frames are evenly spaced.
An 8 frame, we have not gone that way yet. I can therorize the comb having deaper cells. But depending on your uncapper, you might end up with more cappings, causing the bees to have to rebuild more each year.
You have to remember to minimize the space between the frames to decrease the funk waste combs.
However, in brood chambers, always 10.
Are you using deeps or medium supers? How many hives? A good web forum is "BeeSource". If you go there, I am "Honey Shack"
I'm looking at getting a kit. I'm just starting out. I've got two books. One says to use 8. The other says 10. Most of the honey will be for home use. Later on that may change. The supers are 9 5/8" for brood and 6 5/8" for honey.