Honestly, I'm not sure.
I'd press the blue button in a second if it meant I got wings. I don't want that Superman shit though. So if I couldn't get my wings, there are a lot I'd consider.
Red would be a really good defense mechanism during crucial moments. Also I could explore areas I'm not allowed in without getting busted.
Grey would also be cool although I don't know why I'd pick it other than to seem cool and surprise people. Actually I guess it would make for a good defense. If you're being shot at you could stop a bullet and send it up in the air.
Pink sounds really helpful but it doesn't really provide any good defense against others so I could be captured and misused for it.
Green would be cool because I'd gain the ability to roam the world in a variety of different ways. I guess if I wanted wings, this would be another way. And omg I could explore the ocean too. Yup, I'm voting green.