Two Options...

[Hotfoot]

Flight. First of all, it would be wonderful to use to get from place to place. Secondly, it would be better in some situations for sneaking up on people than invisibility. Think about it, what good is it to be invisible if someone can hear your footsteps? If the flight ability is anything like in almost every single superhero comic book, then it is completely silent. It also gives you all manner of tactical flexibility, such as being able to enter a building from any floor, rather than having to slog around going up or down places.

[Vympel]

Hollow Man anyone? Boy, that movie SUCKED ASS.

[2000AD]

The first thing into my head was what always comes into my head: It depends ...

how fast i can fly?

what altitude can i reach?

will i go blind if i become invisible (due to the simular refractive indexes therefor no light focussing)?

will my clothes become invisible too?

will i be able to change between invisible and visible at will?

Assuming i choose the limits i'd go with invisibility.

[jegs2]

I chose invisibility. See too many advantages to that. Of course, I'd still show up on infrared sensors (nuts)...

[Sokar]

Invisibility , primarily for the massive perv factor plus the potential for mischief and mayhem

[Gandalf]

My first thought was flight, because it allows almost total freedom, and how cool would it be in a one on one fist fight?

[Cyborg Stan]

Invisibility, by a narrow margin. With invisibility you can hide your powers. Even if you make a bit of noise when moving around it would be still be hard to figure out it's you. Most people would probably think they're crazy or there's a ghost. You can also get into places easier, which I suppose helps a bit but you have to time it people don't get suspicious. You'd also have to be extra careful around blind people.

Flight is interesting in itself, considering in lucid-type dreaming I usually end up flying to get around from place-to-place.

(Not only it's faster and a bit more fun, but the way I do it when dreaming is actually an interesting mental excerise. I have to exert a constant mental pressure of sorts to keep off the ground, a little more mental pressure to rise up or hit the brakes, less pressure to descend (or relax it completely if you don't mind going down fast) and an uneven mental pressure to move in the horizontal plane, which is somewhat slippery. More often than not, I also spend a bit of my attention to make some sort of invisible shield for my face so the wind doesn't it too badly - helps keep my face at a reasonable temputure and makes me able to breathe and see in comfort. At higher speeds I usually end up dressing myself in heavier clothes so I don't get cold and carrying stuff is slightly awkard because you have to adjust the technique. The limitations here seems to be how well focused one is - faster speeds require both better mental focus and protection.)

The reason why I didn't chose flying this time is because it's a bit too noticable. I'd have to take even greater care to make sure it's not noticed, and those attempts to do so would still be more detectable than invisibility. And if people notice you flying, you're an instant celebrity, something I would not want. There would be a bunch of wild fans or angry mobs at my door, and even though I could escape pretty easily I still need to sleep sometime. I'd probably get alot of press on how I'm the Anti Christ or the Second Coming of Jesus, I'd probably get morons who want me to heal people or bring back the dead, or other morons that will automatically persecute anyone that came into contact with me. Those that aren't doing anything to me would be laughing at skeptics for previously not believing every single stupid thing, and pseudo-science industries and medicene would probably sky-rocket. This is despite the fact that while the flight would probably be a super-natural type power in this case, the skeptics were correct for their non-belief at the time and the idiots still would have been stupid because their belief was supported for all the wrong reasons.

Of course, if it wasn't for this minor detail I probably would have gone with Flight. I try to make myself invisible enough as it is.

[SAMAS]

Invisibility would eventually bring too much of a power trip. No matter what you thought about the movie Hollow Man, this one quote holds true: "It's amazing what you can do when you don't have to look at yourself in the mirror." I would pick flight. It's simple, fun, and not immediately abusable. I mean look at the previous posts. Everyone who's picked invisibility has almost immediately brought to mind something perverted or evil. The only real thing Invisibility gives you is the capability to do something you normally won't do because of fear of getting caught. Flight actually gives you something. The ability to move in ways you coundn't do not because morality or fear of punishment, but by physical limitations.