I think that while all three provinces have many great opportunities for deer hunting, it certainly depends on exactly where you go. I have hunted all three successfully in the last two years, but I won't say where!! In all three locations, I had tremendous hunts.
That being said, I would have to say SK and MB are pretty much neck and neck for number one with AB a very close 3rd.
And as far as the taste of the meat between the three, I couldn't tell a difference. Or at least I don't think so. I would more peg any differences to ages of the animals.