I wish I had the power to replicate matter. It'd be really convenient to always have some extra money, or to have two of any electronic device for when the first one craps out, or to have multiples of a family heirloom to give out. I know you can pretty much do this by being rich, I just love being saved the inconvenience.
other powers I'd want include:
3. Invulnerability to damage and disease
4. Shape Shifting
5. Power to Mimic other powers ;)
I wouldn't want any power so dangerous that I felt like a threat, or so helpful that I'd feel burdened to help humanity. I heard of a story about Astro City's Samaritan or some other Superman stand-in who felt crushed by his burned to help humanity, knowing whenever he stopped for a latte exactly how many people who be injured and die. Accordingly, my powers have mostly novelty value.