Controller + Model vs Ultra-slim controller that barely does anything + Library

@InsiteFX
Thanks for your answer!
It doesn't really matter to me right now what I will be using client side. jQuery, "pure" JavaScript, or even no JavaScript at all and simple site refreshes instead. What I have problems with is my back-end structure, where I can't decide between multiple ways of doing it and am not even sure if any of my ways could be considered "good".