You know, looking back at my original post here, made when I was...gosh, 14...I really think I need to update it. And if anyone actually reads all of what I'm about to type, you can have a cookie.
I have always been fascinated with the concept of shapeshifting. That still hasn't changed. But I think now, I am a lot less "Oooo, changing into anything would be awesome." Hypothetically, if you did not have some kind of limitation, it would be impossible to be able to use it effectively. By that I mean with pretty much every power at your disposal (loop hole!), it would not be feasible to master everything you could do. You could change into so many things, yeah, but with any kind of power you need to learn to master it. You may be a master of shapeshifting, but how many of those things you can shapeshift into are you a master of its power?
If you were to just limit yourself to being able to shapeshift into just one or two things, it would probably make you stronger in the long run since you only have a handful of forms you need to master the powers of. In fact, the show American Dragon is what kind of made me start thinking, maybe being able to turn into anything isn't so great. Jake turns into a dragon, but barely has any handle on his powers. So, if its that difficult to learn one form effectively, how on earth can you learn to use multiple forms?
Actually getting to my point, I think you can tell my idea of a good power would be being able to shapeshift into one thing. If you asked me maybe three years ago, i would have said either werewolf or dragon. Interestingly, knowing how I am, and how much I love the supernatural, cryptozoology, evil creature field...of all things demons never once crossed by mind as something cool until I played Brutal Legend (where the main character is a half demon)...
So yeah, this entire post was a roundabout way of saying being a demon (but with the power to shapeshift between human/demon...preferably some kind of bat demon. Because bats are awesome