I haven't got the energy to get into the "ideal system of government" question here, but I want to note that a key issue in the US is that the "checks and balances" of the current system are quite strongly predicated on various actors, particularly those in Congress being more beholden to local forces than national parties.

Thanks to changes in the social/technological/media/money-in-politics landscape, that assumption is becoming untrue.

As such, the US system is sliding towards becoming more and more parliamentary anyway. That in itself might not be cause for concern per se (the French system is quite a hybrid, for example) BUT the slide towards a parliamentary level of party power in the US poses critical challenges for the "checks and balances" system and that does seem an important and worrying issue.