I was using the gopro software. It is free. It was working good (just slow, but that's my hardware). It would probably do most things in the beginning, until you want advanced options. I stopped using it before I finished my 1st edit because of my hardware.
I did find an app on my android tablet (tab 4 10) that I can cut and splice videos. It's called Vidtrim. It wasnt great by any means, but I could import videos to my tablet from my go pro via bluetooth then cut them down real quick, and its basic version is free. It is a good alternative to messing with my computer.
The software on the mac worked good too, but I try not to use my Wife's work laptop for such things.
I could never make Window Movie Maker work. I tried updating the codecs and what not but could still never get it to work with the mp4s.