I own both the Lee and the Forster bench priming tools and have use a friend's RCBS.
RCBS: I didn't like the double stroke action required to prime a case; it seemed like wasted motion...but I could get used to that. What I hated was loading the primer tubes, because I hate the hunt-n-peck. If I had one, I'd be filling the tubes with an electric tube filler.
Lee: Don't have to handle the primers at all. Dump them into the tray, shake to orient, close tray, and insert into the tool. It's weakness is when it met a friend who didn't know the difference between "fully seated" and "brute force". He ended up breaking the shell holder retaining collar...twice.
There is a technique to using the lever. You can't ride the lever after priming a case. You have to release it, otherwise additional primers won't feed down the chute
Forster: This is a solid tool which has the advantage of having the primers facing away from you when priming. The downside is that this limits the tube capacity to only 50 primers.
The nice thing is that you don't need shell holders and the primer tubes are easier to fill than the hunt-n-peck technique
If I had to do it over I would have looked real hard at the Forster, but wonder about the adjustable case holder (the one on my Co-Ax isn't the best and often cases slip out when priming)...
As in the video above, the adjustable shell holder is adjusted by placing a case over the primer ram and sliding in the three jaws to hold the case head in place before tightening the retaining bolts with an Allen wrench....I center the case by pressing the ram into the empty primer pocket. This holds the case securely to firmly seat your primer completely.
I'll sometimes use the Forster to seat primers fully which are left a bit proud when being primed through my progressive press
From the instructions it seems that with the Forster you have to push each primer into the tune (oriented sideways) or get the extra accessory Primer tube loader?
The attached tray, below the lever arm, is used to align the primers. The primer tube is inserted into the cutout, in the perimeter of the tray, the tool is tilted up and the primers are poured into the tube. You can invert the tube for primers not oriented correctly
The Primer Tube Loader is for folks who have attached their tool to their bench or another surface that would make it awkward to tilt the tool. The loaders tray has serrations to assist in orienting the primers correctly before the tube is inserted and the primers are poured into the tube