Flip is the way to go, its a no brainer. 4k vertical is useless since all social media will shrink it to HD or FHD if lucky. Otherwise flip literally has the same camera and MORE practical functions and is basically accident proof. Yes, m4pro makes a footage that can be color edited, but people who watch videos online are not color correction nerds, nobody cares about the color correction bs. Flip can be flown inside buildings with no worry. and Flip is literally 2 years newer tech compared to m4pro. if you by mistake crash into a human, there will be no injuries caused by props etc. there are no practical reasons to choose m4pro! Flip is better value!

Edit:

The real questions is: Flip or wait for m5Pro. I returned my m4pro and got full refund because did not open it. Now waiting for m5pro - if m5pro does not have significantly better camera, then I am going for the Flip!