How effective is defensive play in winning championships compared to offensive firepower?

Let's say that you find yourself in a position to manage a team in NBA, which playing tactics would be your favourite when it comes to looking at winning the championships? Are you going to be an offensive or a defensive coach?

How effective is defensive play in winning championships compared to offensive firepower?

Sir Alex Ferguson said that attack wins you games while defense wins you titles. He went on to win 13 English Premier League titles for Manchester United during his tenure from 1986 to 2013.