The Keystone holders are nice but expensive, but they do not fit most protected 18650 cells, and I don't like the PCB mounting options.

I designed my own 3D printed 18650 holder for my project, including a positive battery tab cut-out to prevent reverse battery insertion. I get to decide how big the battery can be, and protected cells are 100% the way to go.

I've never had a problem with a short with the protected cells, and my circuit also cuts off power to the load using a mosfet, if a short ever occurs. It's been working great for years.