Years ago I would have said RCBS, but not anymore. I use Hornady's Custom Grade New Dimension Dies now. When and if I get the chance I will replace all my RCBS with these. I just bought a new 7mm Rem Mag die last weekend and I have two RCBS 7 mag dies. The reason is a couple or three weeks ago I was loading some 140gr TSX for this caliber. Did all the brass prep, carefully weighed all powder charges and then went to seat bullets. Got the OAL with my Stoney Point gauge and set my die and got the first bullet's OAL set and seated about three more. Measured them and had three different OAL's! Checked the die and its components, all was tight.
I grabbed my Hornady 7 WSM seating die and set it up with the right OAL for the 7 Mag based on the first bullet and the reading I got from my OAL gauge. I re-seated the "next" three and checked; all perfect and consistently the same! I checked everyone for about 20 rounds and I bet there wasn't .0005" difference in those twenty rounds.
There are other more expensive dies out there. Not sure that they're any more capable of producing more accurate ammo, but for now Hornady will get my hard earned dollars for their dies. JohnnyK.
"The only thing necessay for the triumph of evil is for good men to do nothing."