It’s a bit subjective without fully seeing the end goal. But flexible vs rigid ducts aren’t going to have as much of an impact in some of the concerns you bring up.
As with either, the shorter and less bends the better. So a big benefit to a rigid inside the tent would be easier to clean, mold resistant, easier to manage and attach. Flexible is just meant to be cheaper and provide better maneuverability. As with any ducts and a well sealed system you create resistance in the airflow. Less resistance less energy consumed and your equipment will last longer. For short systems like these it’s less of a worry but having small in-line fans will still have to work with each angle and bend. But if any of the ducts are an intake, keeping them free and clear of any objects generating heat is important unless they are insulated.
The way my current system is setup is a straight line from the filter to the fan, with a 160 degree bend dropping to the outdoor exhaust duct.