Between Camco and Maxxair, I don't see much bad about either one to be honest. Personally, I love Camco products.
As for air flow in general, it doesn't HAVE to be on the roof.
I use my TT in rain and snow. A lot. In those conditions, opening a roof vent isn't ideal.
The bathrooms of most TTs have small windows. If that window happens to be under the awning, open that one instead and use a small battery operated fan.
Any protected window would work for that matter. Most TTs aren't air tight. One open window usually takes care of condensation issues. A fan in front of it works for air circulation