Definitely invisibility - I think it would have much more upside to disappear and escape different situations/acquire pretty much anything you wanted than to just be able to take flight on cue
So you would use your super powers for evil, huh?
I gotta go with flight. If I'm invisible, no one else really knows it and I can't show off. But if I could fly, I could land right in the middle of Times Square with my cape blowing in the wind and my muscles rippling and all the people would be like - "YOU'RE SO AWESOME!!!!"