For me there is not a second's thought required. I would want the power of teleportation, to be able to envision a place I have once been, or can see on a computer screen or paper, and teleport there simply by thinking about it.
Jumper is one of my favourite movies. It focuses on a "Jumper", or teleporter, who is on the run from an organisation determined to vanish people who "don't deserve power that should only belong to the gods". The protagonist shares the same abilities as mentioned previously and also possesses the ability to teleport people and objects of great magnitude with him, simply by touch; I encourage anyone who hasn't already seen the film to check it out. It really made the idea of teleportation that much more cool and fascinating to me.
To be able to be present at will, at any location that can be seen or imagined, is extraordinary to say the least, and far more fun to me than flying or reading minds, as most commonly mentioned by people who would want powers.
Scientists have already managed to teleport a photon (a microscopic particle of light) across a distance in excess of 20 kilometres. Take a quick look at the link below:
I am keeping my fingers crossed that divine intervention will intercede and make human teleportation a reality.
What about you? Comment the superpower you would wish to have and why :)