Having several regular RCBS sets in a variety of sizes, one competition Redding set in 30.06 Ackley Improved, one RCBS Gold Medal set in 338LM, and one Wilson Seating Die for an Arbor press, I don't find a huge amount of difference from die to die. The Redding, Wilson, and RCBS Gold Medal sets have micrometer seaters, which I really like. The RCBS Gold Medal set also has the cut-out so you can insert the bullet from the top----I love that. Run-out varies a tiny bit in the three more expensive die sets, but wasn't that terribly bad from the regular RCBS dies.
I do use Sinclair's split locking rings on all my good dies, as they are easier to set and stay better than the RCBS ones.