David, by polish are you referring to a friction polish?
If so, in some ways it is not as durable as CA. However, it is a finish that you can easily keep up - apply a light coating of Renaissance Wax or other microcrystaline wax every once in a while. It will still patina with use. They are typically shellac based. A CA finish is more durable, per se, but once it's scratched, there's no easy repair outside of disassembling the pen and refinishing and scratches/scuffing show real easy in a gloss CA finish. Also, I've been doing some research and have been finding that CA finishes may not hold up in the long term - yellowing is a possibility.
Right now I'm using both friction polish and CA and finishes, depending on what I'm wanting for a finish on the pen I'm making. However, I'm also currently exploring other finishing options, such as poly or lacquer for a finish that will possibly have longer longevity. Might give Les' poly dipping a try. Or I might use a brush on finish and a slow speed dryer I have and give that a go.
The reality I'm finding in finishing pens and other small turnings and in researching finishing alternatives, there may not be a "perfect" finish that checks every single box on the checklist of what you may be looking for in a finish. It may come down to which finish has the most desirable traits that you're looking for, along with negatives that you can live with. Just my opinion from my limited experiences.