Remember Churchill's aphorism about democracy? Maybe the same applies to the US. Think about it. Look at the really powerful countries in the world right now and decide which one you would want with the title of "The World's Superpower"?
Don't nominate Costa Rica okay? This is about realism. China? Russia? Not bloody likely. Out of the three the US gets my vote. Britain? Hmm, relatively benign now but have you seen their history? What if they had a relapse? Mutiny and they stick you at the wrong end of an artillery field piece and put one up the spout and suddenly you're sprayed all over the desert, no thanks, might give them a miss. Germany? Maybe, at least things would be organised. France? Perhaps, at least the food would be good.
Italy. Okay, it would be chaos but it would be bloody good fun.
Nope, seriously, the US has my vote, warts and all.
Thou shalt not follow a multitude to do evil Exodus 23:2