3. Inception
This might be a controversial choice, and there could have been a number of the more standard heist films in its place (such as The Killing or The Score) but the very reason I chose Inception was because it inverts the tropes of the heist film - the gang are breaking
in not to steal something precious but to
plant something instead, and it isn't a bank or gallery they're going to do this in but someone's subconscious. Inception retains a lot of the recognisable aspects of the most succesful and fun heist films - good and varied gang of characters with their own distinct personalities and motives, and intricately thought out plans - while using the concept to add its own unique threats and dangers such as Cobb's dead wife in place of the law to throw a spanner in the works, and using the subconscious as a means of creating fantastic settings for the heist to run its course. I call Inception 'Ocean's Eleven as written by Carl Jung' for a very good reason!