I'm friends with (recently retired) SSA Buford Boone who used to run the FBI Ballistic Research Facility, and in my last job, I did quite a bit of research on ballistics: terminal, exterior, and interior. I'm not going to get into an argument about ballistics on the Internet because that's just silly, but I will tell you that I know for a fact that the .357, overall, is not a superior performing caliber in terms of terminal ballistics compared to the .40 or even 9mm. This is backed up with hundreds of data points using gelatin, live tissue, cadavers, high speed photography, and many bullets, bolts, and barrels. As a matter of fact, SSA Boone had concluded just before he retired that there is a superior performing 9mm that he believes all LEOs should carry, but the .40cal bonded ammunition he chose for the FBI is currently the "second best" in terms of an everyday carry for LEOs. His personal opinion is that all LEOs should carry rifles, but he was never able to conquer the politics of that one, and that's an entirely different discussion. You mentioned the USSS, and the day before SSA Boone retired I was in a meeting with him that was cut short because the USSS was coming to talk to him about his latest pistol cartridge research. The USSS relies heavily on the FBI's research, and the firearms industry at large for the latest developments. Nearly every year they do another down-select for a new rifle or a new bullet based on changing requirements and new research. They also don't have standardized ammunition across the entire Service like the FBI does across the Bureau. Anyway, what I know about ballistics is shallow compared to a lot of folks I know, but what I do know is that it's an ever-changing field with very few true experts, and the true experts that do exist in the field I happen to know personally or can get to with one or two degrees of separation. So, I can comfortably say that amongst themselves they will never say verifiably what the best bullet "period" - they always add the caveat, "for your circumstance and based on my experience, but...".
You could also get into the argument about which is better: fewer, larger misplaced holes; or more, smaller misplaced holes? Point is, there's no real sense arguing about it. I carry a G19 as my everyday carry. :driving: