It’s up to the individual runner to pick the lead that is the most comfortable to them and that ultimately gets them to the next base fastest. Keep in mind that won’t be the same lead-off for every player. I know that most coaches in softball think that every player should use the rocker-step lead off and yet if you watch the US Olympic Softball Team play you’ll see all 3 types of lead offs (the 3 types are; the rocker step starting with your body behind the base, the rocker step with your body in front of the base and the baseball-type leadoff where the player faces the batter in their lead off). Going back to the US Olympic Softball team Jessica Medoza uses the rocker type leaf-off and Lisa Fernandez prefers the baseball type. What you need to do is have each player try each of the different lead offs and let them pick which one is more comfortable to them – keeping in mind that even if they pick the rocker type they need to try it both was (with each foot forward). Then you need to line them all up at first base, have them use the lead off you want them to use and time them running to second. Then have them use the lead off they prefer and time them 1st to 2nd. They should do it 3 time with each lead-off in order to really see which one is fastest for them.