I haven't stayed at Cherry Hill, but have lived in Washington, DC/Northern Virginia for 40+ years, and the superior METRO access from Cherry Hill makes it the winner. They're geared up for tourists and provide lots of information, too. The reviews say it's a nice campground, if a little expensive compared to city/county/state parks.
There are some nice county parks on the Virginia side, but no easy bus from campground to METRO that I'm aware of. You can drive to METRO, but commuters fill up the lots early Monday-Friday, and it's another $4.50 for parking, IIRC. Unless, there is a reason to be on the Virginia side, I'd stay at Cherry Hill.