re: Which button would you press?

Blue kinda gets swallowed up by green, since you can just shapeshift into a bird.

Hard choice between Green, Grey, or Pink.

Grey you could do a ton of shite with, it would really depend on the strength of the power. Green would be a lot of fun in a lot of ways, pink would be the least fun, but the most useful for making money.

I'd have to say Grey or Green would be it.