I mainly do circuits classes and am on the browse for a fitness / exercise watch. I don't know whether to go with the FitBit hype, guess they must be great since they are so popular. I have also heard of Garmin. Really, I am looking for a watch that tracks calories done during a class (appreciate it might not be accurate) but just for an idea and to try and push myself a bit further. I would be keen to know what other things these watches track? Sleep etc? With it being a first purchase I'm not looking to spend loads. Ideally less than £100 but really just keen to find the cheapest option. Thanks!