Better camera may well be subjective, but the Cube+ has crazy aliasing in low light. We tried one as a smaller GoPro alternative, seeing as the project we were working on at the time was a web delivery with only a 720p master, but the Cube+ gave us such bad results on set we ditched it really early. In bright sunlight, the Cube+ will be as good as the Hero 4 Session I think, but having not tested, I can't say for sure.
I'm very interested how the Blackmagic Micro Cinema Camera (BMMCC - they need a better naming system) will turn out. The fact that it has a global shutter excites me a bit, but I have yet to find a good MFT lens that I'd be willing to put in a crash cam situation. Anyone have any recommendations?