Absolutely invisibility. Dude, you could pretty much do anything you want if you're quiet (even if you make a noise, it would probably take people a little while to figure out there's someone invisible standing there, and by then you'd be long gone!) I'd use it to avoid people I don't like, scare my friends, go into restricted areas (what's REALLY in Area 51?!?), get free stuff.. If one went invisible and stayed invisible, no one could ever bother them again.
Besides, no one's going to call the government when they think they hear someone breathing and no one's there. But I guarantee they'd be very interested in questioning and studying some guy or gal who just took off from their front lawn like it was nobody's business! That could cause complications.
Flight, preferably with big feathery wings. Something about invisibility bothers me, if all your tissues allowed light to pass through...wouldn't one be blind in that state?
Flight, despite my fear of heights.
I went up in a helicopter once, didn't mind the up part, it was the getting up and down that scared the crap out of me. XD;

Flight of course, I'd like this feeling of unlimited freedom. And falling..Oh God! of course flight!
Flight because I could escape and go anywhere in the world. Plus the beautiful scenery I'd be able to see.
Invisibility sounds tempting but it would backfire on me. I'd end up hearing things said by them about me that I was never meant to hear. I'd end up never trusting my family and friends.
mmm, I need specifics here. So if one could fly, is it just as you? Like Superman style? I wouldn't want to been seen and cause a huge stir you know. But if I could choose a power, it would be shape shifting. Then I can just turn into a bird and fit right in.
But anyways I'll go with invisibility.
Well, what's your flight speed? I could see myself taking that so that I could just go where I want and not worry about transportation but I don't think we're talking like Superman flight. (especially since our fleshy bodies couldn't handle that velocity.)
Otherwise I see myself as more of an invisible person. Easy way to always have the money I need, lol.
(To be honest though my power of choice is teleportation; pocket dimension edition. Kind of the best of both worlds.)
Neither. I'd rather be a power thief or have mind control
If we're in my own little fantasy world where no assholes live so I don't have to worry about consequences, Flight 100% I have always wished I could fly and would love that feeling of freedom. I would never touch the ground again!
But in this world where freaks are dissected and you'd more likely get shot down... And as a mother who often wishes she could find maybe 5mins of solitude... Invisibility. Definitely. And I'd use it with a bowl of ice cream LOL There would be it's own feeling of freedom just to be able to not be seen for a moment. I'm not sure how often I would use it, but it would be a nice option to have lol
But flight and invisibility are both my faves! Danny Phantom has the best of both worlds. I would choose flight overall because I love heights, and it would make travel a whole lot faster.