I am with you at something: Man City can't buy the best players in their first year.
They need to look for mid players, they will attack Premier League title for 2 years and if they get Champions League Place, there will come some better players.
I believe Villa will come to Man City, but don't forget about Spurs, I heard that they will pay around 50M for Villa.
And Aguero won't come 2 Premier League, he will join soon R Madrid or Barcelona.
Man Utd doesn't need anymore players, they are a complete team, but if Ronaldo leaves...I don't want to look in future for you...