I'm using DaVinci Resolve Lite with my X5R camera, it's free up to UHD 3840x2160 image size output and directly open and play the raw files of the inspire.
A friend is using Edius with his GoPro, they have a free version too.
Premiere, FinalCut, AVID are good but they are paid and can't work directly with raw files like DaVinci.
There are other free softwares on the net but I can't recommend any of them because haven't tried them. All of the above will do perfect job.
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