I own 3 action cameras. GoPro hero4 Adventure, SjCam legend6, Sjcam 5000X. Among all the three the color production which gopro gives is uncomparable with the other.
But GoPro over exposes the scene where as Sj Legend perfectly couples the exposure and Sharpness.
Though I use all the cameras simultanously on my helmet, I would prefer Sj Legend over gopro. Main thing is Price. Both supports 60fps, same video quality, almost same features but with huge price variation.
If you have a budget concern, go for SJ legend. If you have thousands in your pocket without knowing what do to, go for GoPro.
But I have to admit that gopro lens is something. It does magic with color production!