While I do agree that forms of Democracy are the best we've got, I hate to be so absolutist about the American form being "The Best".
Our infrastructure locks us into a two party system, it is just about impossible for a 3rd party to get much influence, or even enough influence to make a difference.
It's not at all uncommon for a single Party (either Democrat or Replubican) to have control over both Houses of Congress and the Presidency, and with that, there are really little checks and balances, other than The Supreme Court (YMMV on wether you believe they play Politics or truly vote in their best conscience, it's my hope most of the time it is the latter). Locked into only a two party system, there is often no need for compromise or coalitions.
I'd have to know more about other Democracies' multi-party system to know if ours actually is the best, but, I'd certainly like to see the two party stranglehold broken with a viable 3rd and/or 4th party having the ability to have influence