What surprised me is that none of the people he included in sound bites, nor John Hodgman himself, ever even alluded to most of the things that came to mind first to me. So before you read what's below the cut here, I'm curious: What do you think? Which would you pick, and why? What would you do with it?
Edit: The reason I'm asking this question is to find out what you think are the reasons why you might want flight, why you might want invisibility, and why you'd pick the one you pick? (Before you read further and see what came to mind when I thought about it)
Well, okay, what came to mind first was that flight would be the more practically useful superpower, great for errands, travel, impromptu visits to friends, commuting, and sightseeing. One of the people quoted in this radio piece did make the point that flight was very useful for practical reasons like that.
But my next thought was, being the only person in the world with flight would make any use of it very conspicuous and attention-getting. You pretty much couldn't use it for practical purposes like that, because of all the attention every single use of the power among other people would bring. Too distracting, too much of a hassle. Very impractical.
Invisibility is clearly the better choice. You could let a few close friends and trusted people know, but you wouldn't have to make it public, and you could use it frequently. While not quite as useful as flight, it'd still be useful: Going through a scary or unsafe area. Watching wildlife, and being able to get closer than usual, would be wonderful. Yes, animals can smell you, but you might be downwind, and if you're sitting quietly they'd certainly get closer to you than they would if they could see you. Or journalism! You could visit war zones without becoming a target, go to political events and not get treated weirdly or alter the discussion by your mere presence, things like that. Journalism is something I'd do more of if I could be invisible. It might also make it possible to travel to countries that normally wouldn't let me in, or that it'd be dangerous to try to go to openly.
But all of these uses of invisibility that I thought of weren't mentioned in the piece at all. All people talked about was spying on friends, family, and coworkers, or seeing people naked. Which, come on: the main reason most of us don't do these things isn't because we can't. You can find ways to do them and not get caught if you really care to. We don't do them mostly because we think they're wrong or creepy. Invisibility wouldn't change that.
I'd certainly expect some of the people in the radio piece to have very different views from mine, but I thought the things that came to mind for me were obvious enough, or plausible enough, that I'd at least hear some of them, from someone. Now I wonder whether I'll see any of them from any of you who read this, before you read my whole post.