Onside Kicks are attempted with all players stacked on one side of the ball or not. The theories of element of surprise versus creating a numerical mismatch duel here.
Another option is to have the kicker try to pooch the ball just over the front line with ones own team sprinting past the would be blockers. The kicker should try to kick the ball in such a way as to cause it to bounce high in the air. This should be a regular drill for the kicker in practice.