There isn't much to choose between them with recent designs which should all avoid any interference to gimbal starting up.
You probably only want ND8 ND16 and ND32

IMO the regular user has no need for them even if they are expecting decent video from it to upload or whatever.Because the typical drone video subjects are not especially problematic with higher frame rates than is advisable.
Since the Phantom 3 camera doesn't have aperture control, you can only slow it own somewhere near, you can't fine tune to get the 180 degree rule to work exactly.
Additionally you will typically be looking up/down and turnig -  which requires constant changes to exposure anyway.
For the most part you are just as well leaving it on Auto exposure and make the best of it later. Lock your white balance though, that is too hard to correct later when it changes during a flight.