"It is far more important what you do with the dies, than which dies you are using. "
Roger that. There's no particular magic or "precision engineering" to any of them, they are all cut to SAAMI tolerances and that's a range, not a specific point. Anyone thinking if he just gets his tools from the 'best' maker things will be perfect is going to be disappointed quite often! All makers turn out good dies but, on average, dies vary as much within a brand as between brands; including Lee and RCBS.
When I buy a new die set I know what I get will be 'luck of the draw' no matter the brand. So I buy, measure/gage the output and if they aren't up to my standards I'll swap or sell them and try again, often from the same brand, and measure again until I get what I seek. A concentricity gage properly used is the hand loader's friend, it's much more helpful than trying to buy the 'right brand' of dies!
Well, there is a small but fairly consistant advantage to Forster and Redding rifle seaters but few shooters or rifles will ever shoot well enough to see any difference. Thing is, Forster/Redding also have manufactoring tolerances and a good set of conventional dies USED CORRECTLY can equal the much more costly ones. And those of us who use Lee's collet neck sizers correctly prefer it to any costly bushing or special reamed neck dies.
Lee's unthreaded decapper stem is held in a tapered collet to keep it better centered AND to allow it to slip if there's a pebble inside or if the flash hole is off center; that way the pin won't get broken and it works. Hornady recognised those advantages and copied it after Lee's patent protection expired.