Hmmm, hard one.
It is a fight between:
Fighter Ace - Well, it would be fun there is no denying, and you might just be able to become an Astronaut, which would be rather cool. Actually, forget the fighter ace bit, just let me float about in space doing experiments and so on instead!!
The only drawback? Being injured/killed.
Prime Minister - You would be privy to many cool secrets, wield a certain amount of control over the country, you would be able to meet lots of famous people and you would be able to travel round the world. You would go down in history, you would have prestige, and have an AMAZING pension once finished. Come nuclear apocolypse, you would be one of the lucky few to be in a bunker.
The only downsides would be that it would be highly stressful and very high pressure..... Oh yeah, and that everyone would hate you, regardless of what you did.
Nobel Prize Winner - Well, just imagine the prestige and respect from your fellow scientific community peers! You would have achieved something truly amazing and you would go down in history for it!
Wow, go you!!
The only drawback is that nobody would have heard of you and, well, an award doesn't pay the bills.
Self Made Billionaire - Nice, and you would never have to worry about money ever again.
The downside? Just imagine how stressful it would be to start from nothing and run a company to that sort of level! Also, just think of all the people asking, begging and trying to con you out of money. You'd never fully be able to relax.
And finally, would you really be any happier?? After all, money only brings you choice, not happiness. With everyone all wanting a piece of you, it wouldn't be too fun.
With this in mind, if I ever win the lottery then I am NOT, I repeat NOT making it public. Millions or billions, it doesn't matter.
So, with all that in mind, yes, it would be nice to be an astronaut, a billionaire and Nobel Prize winner, but, I think I'd rather be something else!!
A humble soul who is just happy with what he has.