Fighter pilot - To me, being a fighter pilot would be the best, everything about it. You might have to do 7 hours of briefing and all just for a 1 hour flight, but it'd be so worth it.
Next would probably be a billionaire and I'd set up my own motorcycle racing team, and be the rider. I don't understand these people that have won 10's of millions on the lottery, buy a big house, nice car, then sit on their arses watching jeremy kyle saying they're bored! I'd be doing something, every single day without fail. Whether it'd be travelling around the world, or buying some nice cars/motorbikes for me and a few friends and having a road trip to the Nurbugring/around europe. Just anything!
Sorry about the little rant.