There are only 3 important considerations when choosing a CB antenna:

The longer the antenna, the better the range.  There are always trade-offs between performance, aesthetics, and height restrictions, but just remember that the length of the antenna will have a direct affect on the range of your CB.

Fiberglass vehicles must use a “no-ground-plane” antenna.  This is a special antenna designed for fiberglass RVs and boats.  These vehicles need a special antenna since the body is not made of steel.  You can find “no-ground-plane” antennas at places that sell RV and boating accessories.

If you need weather reception, make sure the antenna is compatible with the weather band.  All center-loaded antennas and all fiberglass antennas are compatible with the weather band.  But if you choose a base-loaded antenna, make sure the package says that it is compatible with weather.

Beyond that, it is just a matter of choosing a mounting method that works best for you.  There are a large variety of mounting options available for CB antennas.