We've gone through a decent pile of action cams filming for our aviation TV show. I have to recommend GoPro. We've tried wannabes and they were just that. New GoPros come in lesser, more affordable versions (white or silver vs black). But you can pick up previous generations even cheaper and get TV-grade quality. Case in point, we just upgraded to Hero 4 blacks, and have a few Hero 3 blacks to trade-in for about $100 each (we skipped through the 3+). We also have a few Contours that I can hardly give away! Seriously, GoPro owns the market for a reason and there are many varieties to consider. My 2 cents.
