I bought a sony action cam mini off the back of this test in mtbr. They attached a bunch of cameras to the same helmet.
linky
I went for the sony as it has a remote and I thought better shake reduction. A year on the only thing I don’t like about it is you can’t change from photo to video on the camera itself, you need a remote to do it. Other than that its great.
A mate bought a go pro and footage of similar things is similar.
This video is mostly from the sony and part from the gopro (not sure which one). If its on the side of a head is sony and on top go pro.
[video]https://www.youtube.com/watch?v=yxNpokVnEI0[/video]
By the time its on you tube, there is very little difference.
Any of the go pros will be fine, any of the sonys will be fine. Probably almost any at £200 will be fine. Its more about what you are filming than the camera.