The answers here are not any different in the other thread started on the exact same topic.

The simple fact is that presuming that you are headed to Washington (for the pedants, it is the Ciry of Washington in the District of Columbia), connecting will take longer and carries other hassles than the non-stop to IAD. The exception is BWI, but presuming that you do not want an Uber, you must take a shuttle ride from the airport to the train station and then fight your way out of Union Station once you reach the city.

IAD followed by an Uber will likely get you to the door of your destination in Washington the fastest.