Speaking strictly from parameters on the SPC mesoanalysis page, I'd favor NE Maryland into the western suburbs of Philly today. Weaker lapse rates may be offset by the hillier terrain there as things coalesce.
Normalized CAPE and 12z RAOB from IAD/RNK/PIT would argue skinny CAPE profiles. Shear is also pretty weak too, but the 1.8" - 2" PWATs would suggest isolated flash flooding is the bigger risk, especially around any surface boundaries.