Well, I can only say the Proto 1 piece, only one I've used them with.
-Price (around $35 for 2000 at Dick's)
-Hardly any dimples.
-Could be more accurate
Found these at Dick's for around $35 for 2000, it was either these or $70 for marbs and there's no way I'm paying $70 to play rec ball. I open the contained and was presently surprised at how round they were. HARDLY ANY were dimpled but the seam seemed a bit thick but felt no difference. They were decently accurate and broke on target but the fill isnt all that good, mostly oil o.O. I had 1 break the whole time but was down my barrel.
I would definately use these balls again and at that price you can't beat it. Just make sure you check the container first to see if any are broke or a bad batch.