Hero 3 and 5 both have the same output resolution (512 x 384). You will want to output your video from your video editing software usually at 480 x 360.

The Hero 5 has the newer higher resolution sensor which will result in better video. The Heros also have wide angle versions available now.

I havn't tried the Mino HD yet, but from the specs its worth a look and is most likely worth the extra change if available. The mino HD video resolution is HD 1280 x 720 (double the Hero resolution) and records at an impressive 8.8 Mbps.

Remember, for anything video, resolution is only part of the story. Video bandwidth (aka bitrate) is just as important. You can have the best quality 1920 x 1080p HDTV and if the video bandwidth from the cable company is low for a particular channel, it wont look that good. Thats why a lot of HD folks were using over the air HD signals, they were broadcast at a higher video bitrate than some cable HD signals. To digress a little more, a cable HD channel may run at 5-10 Mbps, where a Blu-Ray disk may be recorded at 35 Mbps. Big difference. Pretty much you get what you pay for, the more you spend, the better your video will look.