FWIW, the GoPro is a good camera but is bad for cycling IMO because it's very blocky and hard to mount well. I owned one, sold it. Also I had trouble with the loop recording - sometimes it would decide it didn't want to do that and just shut off every time I turned it on. Their support was very arrogant and rude, they basically told me it was my fault for buying cheap memory cards - I had bought the SanDisk Ultras that they recommend.

Contour I also owned, sold because it's almost impossible to do anything with it (change settings, clear memory, etc) without hooking it up to a computer.

The Sony I had was a good form factor but the picture quality was mediocre. I had the very first generation sport cam they made. I think they're better now.

I've played with others as well.

The SVC200 I like because it's easy to mount up against the helmet (PM me if you want a very low profile mount for it - I designed and 3D printed it myself). Also it takes standard Nokia phone batteries, so I can get both batteries and chargers off eBay for very cheap and will even if the company goes out of business.