I despise PCC’s. If you want to shoot a handgun caliber, buy a handgun- if you want to shoulder a weapon buy a rifle. To me a PCC is a solution in search of a problem.
That being said if I was wanting to go that route I would go with a B&T 1st choice or an actual HK, Dakota Tactical, Zenith or worst case POF MP5 keeping in mind the 2 latter will probably need tweaking.
A Marlin Camp 9 is not awful although mags and parts availability can be a issue.
The Rugers, CZ’s and AR platforms I have dealt with just beat themselves to death.
I will give you Ruger owners a hint- disassemble your weapon and LocTite every threaded fastener.