i highly recommend anyone installing a dash cam, it can save your ass. example: got into a rear end accident in Aug and the dash cam helped prove the car in front of me was distracted and stopped too quickly, actually hit the car in front of her before I rear ended her ..... so I was able to prove she was the primary at fault party. otherwise, based on circumstances I would have been liable for all 3 cars involved since I was the one in the back.
Go Pro is meant more as an 'action camera' to take on adventures,hiking, biking, skiing, etc. you have to manually start/stop the recording function
dash cams are meant to be in a car - the start/stop is automatic when you turn on the ignition - you dont' have to think about it, they just work. some also have GPS built in to display MPH (nice to be able to dispute tickets) on the recording.