Easy. The power to snap my fingers and appear in my room. No walking home, no driving in traffic, just snap your fingers and appear in your room. You can also bring whoever is holding on to you.
Extra bonus: snap your fingers when it's just yourself and appear in your bed in your favorite lounge clothes.
I want the Super power to always be able to find the Doctor, that includes being able to travel through time and space. :)
I would go for shapeshifting into animals (including fantastical ones)... a little like in Keith's response, I could have flight as a bird, strength as a gorilla, stealth as an insect, and awesomeness as a dragon.
Complete invisibility. Not like Harry and his inheritance, but being invisible to the eye, and all other senses: smell, touch, listen, feel, even sixth sense. So, probably walking through walls, going wherever I like with no obstacles and not being noticed by anyone jumbled into one giant superpower. It's be so convenient.
I think I would really like to control one of the elements. Hmm.... I would probably like to control fire or ice. They are completely different, yet really cool.
About a year ago, my housemate decided to use a super hero wiki page to see which super powers we all had (pressed random page and saw which ability came up). I initially had the 'Hellfire' power; I could incinerate things and cause volcanic explosions...not exactly a heroic power but still pretty cool.
The next time we did it I ended up having the power from mythological titans; a little over powered as I could do almost anything :D