The former Barcelona man revealed that everything was ready for a Premier League move before Atletico came in and changed his mind.
"We had a move to the Premier League in mind," Villa told reporters.
"But then Atleti appeared and within three days all my personal terms had been agreed.
"From a career point of view, they weren't lacking anything. They finished third and will play in the Champions League. They beat Real Madrid in the Copa del Rey. Starting from today the best club in the world for me is Atleti."
It is reported that Villa will wear the number nine shirt at Atletico, vacated by Radamel Falcao this summer.