I've never known which are more common in these pairs; I've always used -dge- on philological grounds: in Old English the J sound was represented cg, as in ecg. In the transition to modern spelling this became not edg but edge; i.e. it was the softening effect of the -e that was perceived as giving g its affricate (soft) sound.

The d therefore just strengthens the consonant, like the t in match. For this reason I hold that the group dg by itself is not pronounced J.

This reason is not very weighty, but I have to decide one way or the other, and that's how I do.