I agree with Lonnie - chose a ball you can afford and stick with it.
Obviously the better the attributes the better but it is all about KNOWING exactly what your ball can do with the various spin changes.
Now here is the hypocritical part - I usually use the Lvl33 Cally but still have some slow meter Lvl 1 Callies in my bag. If I use them on a hundred yard approach I will come up about 6 yards short. Fine if I knew exactly but I don't, so do not use them.
So whatever ball you decide to use, map it to know what the ball can do with all your clubs and various spin applied.
Then the only other time I change is when my timing is so bad I will revert to a Max ball - useless hunks of black dung but they do have a slow meter - problem is they react like a hockey puck on ice with the spin - ie shocking.