Those are all great games. Any one of them will be a great gameplay experience. However, I'm told that Skyrim would be the best game of all time.
Skyrim is not only the official Game of the Year, it's the only one on your list that has months of gameplay jam-packed into the game. The gameplay itself is awesome as you slay dragons and do countless other occupations that gives the game it's variety.
Now I never played Skyrim, but I sure want to. Do what I did and watch some gamplay footage to see what all the fuss is about. Once you've seen what the gameplay is like, you'll most likely fall in love with the game. However, I'll leave that up to you. If you like what you see, then go on ahead and buy it.