Jim, you are right, lock rings aren't the reason to choose a die....choose the die first....then decide on the best lock ring for it based on your experience or perceived or real need. Also needs are different depending on your press, or whether single or progressive.
I've only been reloading for about 10-12 years. Still using the RCBS dies I started with. They have been flawless so never felt the need to try another brand.
I like Sniper's post....and I have found the same thing....I only have to change the years...more like 40-45. But I have Lees and even one Redding set for a wildcat. No Hornadys....and no reason for that except chance, availability at the time, or habit. But I have only one die set experience, less than perfect ... and that from the least likely source, Redding....
and it was totally a one time fluke. Somebody didn't polish the barrel and it scratched brass brand new out of the box. That's personal bad luck, not a diss on Redding....no factory is perfect. (actually that was the latest die I've bought.
and I'll bet nobody else will have that experience)
My first RCBS dies had round rings with steel set screws. Sometime somebody said, "get the Forster round rings with the tightening clamp screw" so I got a few. Years later Hornady made their clamp screws with the "flats" on opposite sides for wrenchability, so I bought some of those.....and I bought a set of Lee nuts with their O rings. They all work....some work better than others in certain cases.
Dillon rings don't even have locks on their nuts. (think...you set them once on a removeable tool head, so why use a lock nut.)
My experience with Hornady rings are fine, but troublesome in my Pro 2000, because the "flats" don't always end up in an easy place to get a wrench on them....and the long edge sometimes interferes with the next station's Lock nut. RCBS rings are smaller and work fine....I tried the lead shot with them, and that's fine, but IME not necessary. Dillon rings are even smaller.....you don't need lock screws if you tighten down once on a tool head and leave it alone.....and that brings me to Lee O ringed nuts....
They are just as fine if you set them once on a tool head/ die plate and leave them alone. Once caveat with them.....don't even think about removing or adjusting a Lee ringed die by turning the barrel...only touch the nut itself......but you know what? .... that's wise with any die and nut.
Oh, I forgot to comment on Walkalong's comment about still needing a "soft" lead shot under a brass set screw. He's got as much experience as anyone....if he likes them, great, maybe good insurance....he's probably loaded and shot more in a year than I have in 10. But I haven't had any trouble with the brass ones slipping, maybe he has.
What I HAVE had is an annoyance with the clamp screws on Forster and Hornady rings. When you set your die and finger-tighten the lock ring, everything's fine....then you clamp the nut...you force the nut threads tighter into the die threads and that REALLY tightens the nut against the press....moving the die up just a little in the process, and requires more than a little wrench force to loosen it. Don't have that problem with set screws or no screws. But to each their own.