Should I get an Intuos pro medium or large?

I am used to a A4 paper of course. I have already saved up for the medium sized Intuos, but the large (if you do the match) is cheaper for its size.

I don't know which to buy, should I save up even more money for the large because of the math and more work space, or will it feel a little too big if I am used to A4, hard to move around and so on? I don't know, my income also isn't that big BTW.

What version should I get?