I'll give the edge to Berto for now. Alvarez too young and inexperienced to handle a world class champion like Berto. Canelo still needs to get past a Mike Jones/Soto-Karass level fighter before taking on an elite like Berto. Against a fighter like Berto, you need to have a very good chin and resistance or a very good defense and Canelo has a good one, but at this point not good enough. For now I'd pick Berto TKO6 Alvarez.
Berto is under rated for the most part, and Alavrez is nowhere near as seasoned. Right now, Berto would smash Alvarez to pieces.
At this point in their careers I'd say Berto. I'm extremely interested in Alvarez v N'dou to see how Saul deals with a tough (yet techically limited) fighter. (Btw prediction Alvarez UD - N'dou brings him into deep waters...but good learning experience).
berto would have to be favored now but i love alvarez. i hope this kid is brought along vs the right competition in the next few years and he stays hungry. alvarez has a chance to be a superstar.
Saul won the WBC silver LMW title against Cuello (Don't ask me what that means because I have no idea what the hell a silver title is). He is defending that title tommorow (or tonight depending on which part of the world you're from)