720p or 1080p? 50 or 25 frames?

25 frames, if you use twixtor plug-in on pr or ae in the future. Not very recommended. If the shutter speed is not reached, the lighting effect is poor and completely useless, and the first two are reached in time. If you want to make something similar to a high-speed camera, there will be frame melting. If you have to shoot an upgraded version of the picture, you still need to use 720p for the upgrade part.

50 frames. To some extent, 1080p.

When 720p is playing on a small viewing platform, if the difference is instantaneous, it will not be noticed, and more depends on your scene. my humble opinion

Take it.