What would it be and why?
I'll start with my choice: Telekinesis. If I could manipulate the physical environment around me with just a thought, well... let's just say I like to build things, yeah? I'm the guy who made elaborate pillow forts when I was young. While I'm not exactly a construction person, I could probably do with quickly assembling small structures and objects on the fly, or even just doing things like typical daily chores.