Don't just rely on prices to make your choice. Handle the cameras and see how the settings are selected and changed. Go for the one that feels best for you in the handling - all of the camears mentioned here will give good images. Also you will find a difference in the physical size of the cameras.
You will be buying into a system, and as has been said, once you are committed to one make, it is expensive to change as the lenses, which will be the most expensive element of the system after you have got a few, will not fit another make (with a very few exceptions). Ask Dave
.
Personally, I don't like small cameras, but you might find the opposite.