"Best" is entirely subjective, and depends on the circumstances. 4K video files are very large and require a powerful computer to edit, much less play (i7 with 32GB RAM and a 64-bit OS, at least). Higher video settings also consume more power, which reduces your flight time.
Framerate gets into one of those preference areas: some say that Hollywood films in 24fps, and if it's good enough for the silver screen, it's good enough for the home crowd. 120fps will let you take slo-mo video, but there you need appropriate subject matter - animals, action scenes, etc. That counts as a higher video setting, which eats the battery faster. Anything that requires more work from the electronics requires more power, and that's your battery.
Personally I'm doing just fine with the lowest setting - 1920x1080x24fps. Then again, I'm not Marlin Perkins on safari for Mutual of Omaha's Wild Kingdom. Flying around my Dad's 18 acre spread filming his tractors at rest and the surrounding area from 400 feet up isn't going to win me any cinematography awards.
As for the more detailed settings like white balance and exposure settings, I have no clue. I pick a preset and roll with it. I'm sure a photography class would help understanding the manual settings. I keep telling myself I'm going to take one someday, but as Creedence Clearwater sang, "Someday never comes".
