I have tried all the rest and I am back to the best.
I have always been a fan of Vamoose. I have been using them since 2005 when they stopped in Tenleytown. I tried others (Greyhound, Mega, Bolt, Washington Deluxe) when the fare wars began. I sacrificed a lot for a small difference in price. The scheduling is perfect for me, as is the locations both in NYC (near Penn)and Bethesda (closer to Rockville and I don't have to take Metro from Union). The bus almost always leaves on time and drivers and baggage handlers are courteous.