I'd highly recommend checking out https://dashcamtalk.com/ There's a lot of great info, reviews, and comparisons. Once you've got an idea of what models you are interested in, check out the forums and do some reading up to see what praises/complaints people have on them. Also, check out videos on YouTube of the cameras that you think you might be interested in.
I got the Panorama 2s and have been pretty impressed with it, but I haven't actually done a permanent install yet because it's pretty low on the priority list. It's got exceptional low-light/night recording which was one of my sticking points when looking for a dashcam. There are a few minor annoyances that I've got with it, but most should be resolved with the next batch of firmware updates.
Here's a snippet taken with the cam: https://www.youtube.com/watch?v=_unw4GDG7h0
Powerucc Panorama2s (v1.12.03 - 21mbps firmware) w/ gps.
Evening/night driving.
Even in 1080p on youtube it looks rather "blotchy," but the actual raw footage is substantially more "crisp."