I have both the RCBS and Lyman turrets. There is no question that the Lyman is the easier machine to use.
The RCBS turret head has a recess up by the bolt that holds the turret to the machine. Within that recess is a iron or steel donut undoubtedly put there to minimize the wear as the turret turns. That donut comes out when you change turrets. BUT it does not come out easily. It almost gets welded in place. Removing this can become a REAL hassle. You can order spares of this little part, of course, but...
Indexing is also easier on the Lyman.
I've got 50 turret heads for my Lyman and 10 for the RCBS. A few years ago the cost of a turret REALLY increased for the Lyman so I bought the RCBS. I notice, however, that I use it less and less.