I always film at 2.7k 30fps. ISO 60 to start, film speed 100. The ISO and film speed can be adjusted to compensate for whatever the light situation happens to be during filming. I always film at 2.7 K that way in post-editing if I need to crop a video and blow it up slightly it will still be very high resolution. I only shoot 4K if I'm doing something that's not doing a lot of movement and needs to be unnaturally clear. For instance a bald eagle sitting it its nest. 4K 60 fps, to admire all that beauty, it's sitting fairly still so there's no motion blur issues to worry about, The beauty of the subject is more important then the cinematic quality of the video. 30 seconds and done. Anything longer than 20 or 30 seconds and not a still subject needs to be under 4K and 30fps. That gives it a more realistic feel. Anyways all of this is just my opinion. I'm sure that there are many professionals that would tell you that I'm giving you amateur advice. But this is what I have found to work the best when shooting with a drone,