it really depends on what you are good at and what you like, i do art at GCSE and it is a LOT of work, lots of people take it as an easy subject but it actually requires skill and effort. I don't know much about the other two but that is what I do know about art (that is the one I would choose of course)
My brother is studying Product Design and, from what I've seen of his work, it looks pretty fun. At the moment, he is developing skills in the digital sector (e.g. creating online graphics) which would open a lot of doors for you careers-wise!