Flash Gordon is the one I've seen most in the cinema. I was absolutely captivated by it as a kid. It must have had a decent run in the cinema as I was very young when it was released.
Related story - My folks were picking someone up at the airport around that time. After they met they went for a drink in the airport bar right next to arrivals and I absolutely traumatised every single patron by playing the theme tune by Queen on repeat with my pocket money until it ran out.
edit: To be clear, the damage was done before my folks realised what was going on. Money. Select. Money. Select. They were quite embarrassed.