I use a hero 3 black
Sharpening is your friend...
what programs do you use
I use corel video studio x6 and 7 ultimate
I also use magic video editor 2015 (way better for adjusting color)
Me I shoot 1080p 60fps. Protune on (unless dark day or night) I set the white balance to RAw (auto is bad if you point in the sun makes everything super dark and harder to adjust)
If you like to edit use protune if not turn it off.
I set mine to medium view as my lense has a scratch on it and you can see it when it's on wide.
Cineform with protune works well if you want a free program just look up on gopro website the software for the gopro hero 2 (it's free)
This was with corel
http://youtu.be/PFmE05WEsFw
this was with magic
http://youtu.be/U5VfKLXnSGE
Now if you get black lines it's the props spining and the sun coming through. If you get shaking it's vibrations balanced props make a huge difference and how you mount it does as well. I use a gimbal so it's steady major difference.
My edited footage looks like a hero 3+ silver... in 1080 so it's allot sharper out of the box. I found the Hero 2 seemed better then the hero 3 for quality of image but 30fps vs 60fps makes a difference...