Hi,
I have an RCBS 5-0-5, an RCBS 5-10, a Lee Safety Scale and a small Jennings digital. All have their good features, but, as w/ any equipment, none is "perfect."
There's a set of check weights on the shelf which gets frequent use.
If I had to reduce the "population" to a single scale, like it used to be, I'd keep the 5-0-5, which I purchased first (around '75) and still measures dead nuts on...
If an RCBS (or any of the Ohaus built scales) is having a problem returning to a consistent zero, be sure to check the pivot knife edges and the bearing v-blocks for debris (you may want to take the v-blocks out and clean them and the area where they're mounted to ensure they are free to move), along w/ possible wear and/or damage to the knife edges... if things are clean and undamaged, the scale's probably ok. Verify w/ the check weights.
Rick C