I have used fairly large quantities of Fiocchi, CCI, Federal, Tula, WPA, S&B primers.
Have not seen any performance differences, except the Federal are more sensitive and are the only ones that will work reliably in 3 of my guns.
I ran a test on one of the problem pistols (striker fired) and concluded the Russian primers were the hardest (or least sensitive) and that S &B and CCI were similar, that Fiocchi would almost work 100% and that only Federal was 100%.
I do find that CCI work much better in my Lee Autoprime tool than the other brands.
Unless you have a pistol with a weak hammer/striker spring, all the primers get good (same) results.
I buy on price. I just bought 30,000 Fiocchi SPs for $31/1000, all in. That is a new high.