I got the Wilson 2000 CB antenna. I drilled a hole in my roof and hardmounted it. I can unscrew the antenna when not in use and there is a cap included for the base. I caulked the permanent plate and have had no leaks... yet.
Antenna line runs under headliner, down B-Pillar and under the step plate at the door to the dash. Permanent, invisible and out of harms way.
Problem with a magnet mount is they get knocked off through low branches and such. That Wilson 2000 is very long, but gets great reception and broadcasts very well.
I forgot it was on one time and backed into my garage. Bent a 90 about 1" up from the base. Thought it was toast... but I bent it back straight and it didn't snap. Still working great to this day.