Region D for sure. Things can and will change by the end of the regular season, but as it stands right now the #1 team from Region D will be rewarded with a first round game against three-time defending champion Salem while Loudoun County, Kettle Run, or Sherando will have an open week. I expect Salem will move up a couple of positions before the playoffs start, but still.
If the top 8 from C and D played each other, I think D would win at least five or six of the games, depending on who played who.