I have 4 Lee units and 2 RCBS units. Each has their virtue and their downfalls. The Lee are very good, but will not accept the WSM, SAUM RUM and other large base cases readily because the ears on the body that the shellholder goes into are slightly too narrow. A die grinder would work to relieve this. I broke those ears off a couple of early models, but Lee replaced the bodies, and I note that the new ones are sturdier. Lee, of course requires their shellholders, [Which are a snap to change] or you can make one from an RCBS by grinding off the bottom projection of an RCBS, & Drilling the hole out slightly larger.
The RCBS units are slightly more powerful, and use standard shellholders, as mentioned. Changing the shellholders is a bit more complicated, but nothing out of line. [The universal shellholder unit eliminates this] You have to watch the RCBS, because if you inadvertently turn it upside down, the priming rod will fall out. [I do hate that!] Additionally, I always get a black hand from the RCBS body [aluminum does that] They both have a place in my scheme of things, but if push comes to shove, I believe I prefer the Lee unit. [I have never crushed a primer with any of mine---just use the exact recommended shellholder] Regards, Eagleye.