In life I have not seen a more dominant team than Spain 08-12. From teams of the past it is difficult to compare and from those I saw I think that the Italy of 94 and France today would be the strongest rivals.
My favorite time was 2009 / 2010. The time of extreme boredom for many neutrals.
At the level of clubs, which I have seen, I would say that Barcelona 2009,2010.