Keeping tables even?

[sations]

This is something I have had a problem with at my tourneys? We usaually play two tables like 8 and 8 then we get to 10 and go one table. Now when one gets to six and one is at 8. What is the best way to pick who moves? We have been trying to do it by positions. Then we get into what if he was in the blinds or what not?