I bought a
Garmin 46 after seeing some positive reviews. Mainly Garmin is a decent brand and I was getting a headache doing research. It works fine, installation was easy. I can remove it quickly. The camera is supposed to provide some collision warning, lane departure, even if the traffic in front of you has moved on and you haven't. I mounted the camera way out of my field of view so I turned all that off. It has a phone app so connection is easy, you can download video without dismounting the camera. I hardwired it to power so it goes on and off with the key and hid the wire under trim, really easy on an old pickup, maybe harder on a newer vehicle. Lots of places install them.
Garmin has an accessory cable, not included, that allows the camera to work when the car is parked. I didn't get that; I might hack something later. Some dashcams allow you to add a rear camera and record both views. The Garmin 46 doesn't do that, which is OK for me but might be useful in an SUV. The camera gets really hot, apparently normal - a GoPro gets hot too. I think a dedicated unit is better than a GoPro. When you look at reviews, look for performance at night, when cheap sensors can be bad.