They are all good. Each level up has its perks, but you may not need them. I bought the Hero 4 Black as I use it to scuba dive and I wanted the 1080 option. Ic not for that, I'd been fine with a lower model of the Hero 4 or the 3.
As far as mounts go, you can NOT beat Ram Mounts. A bit pricey but they are great. If you get it with the ball mount, you can go from machine to machine easily. Just buy more ball mount bases. You put one on whatever you want to mount the GoPro on. I have one on my skis, my bike and my motor cycle. Use the same upper mount on each, just clamp it onto the ball that is on the machine..