I'm not a huge fan of the rise, mostly because the high zone shrinks so much in college. Some will say college batters still chase "that pitch", true, but also because it's hard to judge at near 70MPH speeds the 1% of 100,000 SB pitchers can reach.
At 12u my gut votes for the drop, my heart votes for an off-speed because it's so easy to learn. 3 speeds, all with different effects in path due to gravity, disrupt the batter's timing and bat path.
This is what we did with DD and it's worked very well. She throws a three finger drop, then to slow it down a bit she puts four finger across the seams and has a change up. We work on the rise in practice but don't plan on her throwing in a game until next year.