I’ve had the Swaro ATS 65 up against the ATC and the new Kowa 55. Unless I was getting it specifically for the range or the truck, I’m taking the ATC/STC over the others. For me, it was the eye box that set the ATC ever so slightly above the Kowa and the ATS. If the range is your primary use though and you don’t pack it around at all, then I’d still go with the STS. I think on certain days with more limited light, the additional light gathering could provide a slight improvement.
Might be worth noting that I own the Kowa 66, and I really wanted to like the small Kowa over the small Swaro, but that just wasn’t the case for me personally.
As a final note, my side by side comparison experience had the 25-50WA eyepiece on the ATS.