Do you want to fly? Would you like be invisible? How about superhuman strength or X-ray vision?
My superpower of choice is to be able to speak every language in the Universe - from Elven to Italian, Mandarin to Romulan, cat to bat, and everything in between. I'd like to hear (or receive, if it's a telepathic language) everybody's story in their own language and understand all the delicate nuances intelligent beings can fashion.
Speaking of stories . . . think of the stories these guys could tell. Imagine talking to Thor in Asgardian or being able to translate all the spells from the stacks at Hogwart's (BTW - the best class EVER!).