When you are paint shipping you will typically find better results with a field shop as they go through more paint so they both have fresher paint and know what is shooting well.
You want a fresh paint with consistent bore size to ensure the paint will be consistent from shot to shot. Along with that you want a minimal seam on the ball to minimize drag, and with that said you may experience different results based on finish of the ball.
The other factor in the pricing is generally the level of brittle the paint is. A great accurate ball that won't break when it hits the mark is not a benefit for you! You want to be able to hit and have the ball break on contact, but not so brittle your marker cannot shoot it consistently. From there the pricing can vary also based on the thickness and brightness of the fill color and how oily it is. You want a paint that is thick and difficult to wipe, very bright and yet does not stain clothing.
With all of that said, some of the favorites I have shot are...
Thick bright fill, consistent batch to batch and a temperature durable ball. Can be pricy.
Brittle, consistent paint with bright thick fill. Can be pricy.
Great durable packaging, bright shell and fills. Very consistent batch to batch and very reasonably priced.
1. JT Advantage
Might seem like an odd #1 but it has been my experience. I know many will disagree and it may have a lot to do with the fact that I can get it easily and it is available fresh. It has been a bright fill with brittle shell, consistent bag to bag and the seam is fine. It has a matte finish that I have found to be great when shooting, seems to be less impacted by wind for me. I can often find this for $35-$40 a case which is great.
My .02 cents, other experiences may vary.
Antidote Twister LV1
Cobalt Valken Proton
CCM'd Dragon OC Pump
Phantom VSC Custom Pump
"I Fight YOU!!! Pew Pew!"