GoPro is by far the most recognizable action camera brand, but Yi (a Xiaomi company) has been selling the YI Action Camera internationally for some time. Now, it's available in the US for just $99.95. That's a lot cheaper than a current-gen GoPro, and the app looks pretty solid as well.
The YI Action Camera weighs 2.7 oz and captures 1080p60 video and 16MP stills. That's a little less than the GoPro, but the still photo resolution is higher and the cheaper Heros only do 30fps. The YI camera has WiFi and Bluetooth, allowing you to control it via the app from up to 300 feet away. The app can also be used to preview, delete, and share content from the camera.
Amazon is the exclusive retailer for the YI Action Camera in the US right now. In addition to the camera itself, Amazon also lists cases stands, and more.