That depends on what you want to do with it. I'm using the GoPro Hero HD, which is their second generation camera. GoPro has subsequently released the Hero 2, Hero 3 (and 3+), and Hero 4 series (with multiple cameras in each). The Hero 5 is rumored to come out in October. Each of the cameras (and it varies within a generation as well as between them) supports different resolutions, angles of view, and frame rates. Newer cameras have better image quality, especially if filming underwater. Newer cameras also support wi-fi streaming and remote control and have different battery run times.. I'm tempted to pick up a Hero 3+ Silver to get a wider field of view and better image quality. I don't need 4k resolution yet - 1080p is still good enough for me. Using the Hero HD with battery backpack, shooting 1080p 30fps, I can record 3-3.5hrs of continuous video (approximately 24gb) before the batteries run out.Can I get away with the least expensive one?
My Son has a GoPro, and he loves it! He is a machinist, and he uses it to shoot videos inside his CNC mill. Very cool! Of course, he also uses it when he takes his RZR out and does crazy stuff!
Scott.