Like others have said the GoPro is awesome. I’ve never used the Sony, but I am sure you could find some footage on it online to view.
I used the Hero2 for about a year and recently upgraded to the black Hero3+ for my last trip to dive The LuLu and then Vortex Springs. Going from the Hero2 to the Hero3+ the video quality improvement was amazing the Hero2 footage is great.
In my opinion, the Hero is a great option for your underwater video needs.