Go Pro or cheaper version?

Depending on your budget, I don't have any experience with any of the knockoffs but have had a few GoPros over the last couple of years, the Hero 5 Black has been my favorite, I don't and probably won't anytime soon, own a 6. Having a screen on the back really helps to make sure what you're wanting to shoot is in frame, the voice control eliminates the need for a remote control, and it not needing a waterproof case(most of the time) has improved sound quality compared to previous models in the waterproof case. As far as value, I think the 5 is worth the $400. If you're looking to save some $$ too check the used market. Tons of people buy GoPros then end up using them a couple times and that's it. Used 5's can be had in the $275 range, probably around $200 for a 4, and 3s around $125ish.