I haven't had much luck with dedicated dashcams, specifically the video quality. In fact, the last one I bought from a U.S. seller was so bad as to be completely unusable. So need to be careful that you are actually getting the genuine package, and not a counterfeit.
I'd stick with major brands like Garmin, but expensive nonetheless.
Instead, I've been experimenting with using Android smartphone based dashcams, many of which are available for free. Along with some unique advantages, but just as many downsides.
Some things I like is that the video quality is as good as your smartphone. Which tends to be heads over heals better than most mid to low end dashcams. Plus, the software can utilize the phone's built-in gps to add location data to the video, along with mph and the usual date/time. Not to mention that many Android based dashcams apps are available for free. And you can still use Bluetooth and charge the smartphone while in use. So can receive/make calls from a stereo receiver w/Bluetooth for instance.
But there are also some downsides including finding a suitable mount for your smartphone. The ones I've tried so far result in too much shake in the recorded video when in motion. So still looking in my case.
Another downside is that Android does not overlay data to recorded video, so you can only view these from the smartphone. Unless the dashcam app generates a separate sub-title(.srt) text file that can be read by a media player/converter to view this data when using a computer. But not all apps offer this capability.
The Free Android based dashcam/dvr apps I've had the best luck with so far using a Samsung Galaxy S include:
AutoBoy DashCam - Black BoxAutoGuard Blackbox - Dash CamBoth apps can use the smartphones HQ video - 1080P HD. And both can generate .srt files to overlay data when using a media player such as VLC, or when burning the data over the video using a converter.
A few other dashcam apps I've tried were just too buggy, or didn't provide good enough video quality. In any case, you need to test a dashcam app to make sure its stable with your specific mobile device.