When I was researching these for my cars, I found the reviews here helpful (especially the day and night footage videos):
We review the best dash cams from 2013 to 2020, updated constantly. Full specs & details, sample videos, price comparison.
dashboardcamerareviews.com
For the most part, you need to determine what setup you want, single channel (camera in only one direction) or dual channel (front and rear cameras); then, you need a basic idea of the features you want, do you a parking mode where it will start recording if the camera detects movement in the car while it is off, do you want it to have GPS to record your speed, do you want to be able to live stream your video feed for easy access to footage, etc. Once you get a basic idea of what you want, what resolution and video quality you're looking for, jump to the tables linked at the top of the page (basically giant comparison charts), then find the one that best fits your desires and is in your price range. When I did my research, I found the ThinkWare F800Pro to be the best overall fit for what I wanted in a dash cam and have been very happy with my purchase (but, I'll admit, it is my only experience with a dash cam so I have nothing for an independent comparison). I've been running the F800Pro in my Stealth for quite a few years and just recently bought 2 more, one for my Civic and the other for my Pilot. ThinkWare has some newer ones but I still find the F800Pro better overall as I don't need 2k/4k video feed (1080p has been good enough for me) nor do I really think I need a live stream or cloud based service. Plus, since the F800Pro is older, the price on it has come down a bit since it was originally reviewed.
Anyhow, your mileage may vary; but, that was how I was able to sort through the clutter and make a decision on one of these for myself.