When I started bringing a camera along, it used to be a Canon PowerShot digital camera. I had three different ones over the years. I used to set them up along the trail and have them snap a series of 10 photos, usually a second apart. A minute timer would give me just enough time to hop on the bike and ride into the picture. The cameras were small enough to fit into a jersey pocket.
My first action camera was a Replay XD 1080. Image quality wasn't all that great, but it's cylindrical shape is still what I consider one of the best form factors. It was easy to attach it to basically anything. Later, I owned a GoPro Hero 3+, which I replaced by a Hero 5 Session. I picked the Session for it's small cubic form, an ideal shape for POV chest mount shots. I have a Feiyu WGS 3-axis gimbal for stabilization and a self-made mounting plate that fits between the straps of my backpack.
One year, I decided to buy a Garmin Virb 360. While it was a nice piece of equipment, I never really became friends with it and the 360º footage wasn't as useful as I thought it would. I sold it a half year later and went back to using the Hero 5 Session exclusively. While I've played with video footage, I discovered that I neither have the time, patience nor the skills to create interesting videos. So I don't use my action cams for that. Instead, I use the short videos I come home with to extract photos. Having several seconds of a small stretch of trail ridden lets me pick the perfect shot.
The latest camera that I bring out on a ride these days is DJI's Osmo Pocket. It gives me some options (such as panoramas) that the Hero 5 Session does not have. With its small screen, the camera also lets me set it up just right without having to pull out my phone. It hasn't replaced the GoPro though, which is still the fastest to setup and shoot. As long as both these cameras work properly, there's no plan to replace them.