@edgarblythe,
I used this page as a guide when I got my dash cam, and they steered me straight:
http://thewirecutter.com/reviews/best-dash-cam/
They do a good job of describing what features are useful/helpful, what features are pointless/harmful, and explaining why they think a feature is good or bad.
They do a good job of explaining how to avoid fakes (don't assume it's real just because it is sold on Amazon).
And they point out some good models that are worthwhile (so long as you don't end up with a fake).
I picked the one they recommend for hardcore geeks as opposed to the one they recommend for people who need something user friendly, and I'm happy with what I got.
It looks like they are going to update their recommendations soon.