I'm going to take a stab at this using numbers as I see them.
I try to get all my clubs (except putter) to have the same meter speed. In my case that is 3.5. This achieves the maximum chance that I can be close to ding on all clubs as the speed across the clubs is consistent.
Then I tried out various balls to see which one I could use that would make the meter speed most comfortable. I wound up using Max Pro with a meter speed of 5.
If I average the sum of the 2 (5+3.5=8.5 divide by 2 = 4.25) that results in what I consider the slowest meter I can acheive with my ball/club combo.
I consider the slowest meter speed to be 5 hence the reason I average the ball speed/club speed but you could just as easily convert your way and use the closest to 10 using the sum of ball speed/club speed.
In my opinion, meter speed should compliment consistency. That's why my first recommendation to anyone is to get the meter speed of your clubs to the same if you can! Then worry about the ball.