If you want a proper J product then skip Copa. If you are OK with the domestic F seat and pretty good meal/service options (but cruddy IFE) and want the potential for a quick trip to the Canal on a layover then the Copa option is quite nice.
But definitely a case of getting what you pay for.
Here are some photos and a couple links from my trips on CM last year:
Panama City is Still Amazing
A Weekend aboard Copa Air