There are lots of possibilities but I suppose I would want to be able to transfer time, or age might be a better term.
I would be able to take the time away from someone undeserving like a criminal and give it to another.
I could have great fun with such a power. The surprise of the one who is suddenly aged would equal the surprise of the one who looks in the mirror to find all of their hair is back and wrinkles gone.
Sure; there are lots of other powers and may might seem more useful or righteous but this is one I could really have some fun with.