Well you're going to have to test them all at some point so you know what to keep and what to sell.

If it was me I'd test the carbs in order of how important the carbs are to you. If you paid a lot for them, or if you think they should be the best then test that one first. That way you test the stuff you care about most in your limited testing time. If you have some carbs that you don't really care about anymore then sell them now before you waste any time on them. If you can't sell a carb without trying it then you'll just have to try them all....

Seems to me you need to try 6a and 6b since you've recently invested money into them just to see if they are going to work. I'd think that those would be so close that one of those will get sold. I'm also going to guess that one of those carbs is the best of the litter.