Here are my 3:
1. Teleportation - being able to get anywhere in the world as quickly as the snap of a finger would be beyond convenient.
2. Super Strength - this one is pretty self-explanatory I think.
3. Mind Reading - because it would be interesting to see what everyone is really thinking.
Runners up (for the heck of it): Invulnerability, Flying
Ultimately, I think I would give teleportation the nod...it would just make life a heck of a lot easier. In real-life application, it would be much more helpful than super strength or mind reading...although mind reading could definitely have its perks.