The best action cameras are small sized and have plenty of mounting options, so you can fit them anywhere to capture the action. The best action cameras have wide angle lenses to help you capture more detail. 

We would suggest you take good care of your action camera. Keep it in a waterproof casing at all times, making sure the rubber gasket on the waterproof housing stays clean. You should also keep the action camera inside protective clothing to prevent scratches.

The best action camera: GoPro Hero4 Silver (easy-to-use touchscreen LCD, great image quality,  lots of mounts)
The second best action camera: GoPro Hero4 Black (4K video., most advanced controls, biggest selection of frame rates).
The best affordable action camera: Sony HDR-AS200V (better audio quality, longer battery life.)

A good action camera will capture outdoor action in any weather - attached to cars and bikes, hiking in the rain,... mounting them on all sorts of things, and do all the crazy things.

A good action camera has many mounting options, easy-to-use controls, excellent video quality, Wi-Fi/Bluetooth functionality. They also provide multiple frame rates to choose from , including  1080/60p (Full HD resolution at 60 frames per second). Some now provide 4K/30p frame rates.

They also have big battry life and are light.

The best action camera for normal use: GoPro Hero5 Black (great video quality, waterproof, smart touchscreen interface, voice control, and electronic image stabilization)

The second best action camera for normal use: Sony FDR-X3000 (optical image stabilization,  high-bit-rate recording options, 4K videos)

The best affordable action camera for normal use: Yi 4K Action Camera (all the important action camera features, very affordable)