I’d probably say if you had to select on event you’d probably want it to be one of the jumps. I think ideally though, if you’re really trying to make her as athletic as possible her best bet would be to try several events. More specifically, why not try something like 1 throwing event, 1-2 jumping events, possibly hurdles, and a running race under 800m. It’s no coincidence that decathletes have the title of ‘World’s Greatest Athletes.’ Their many talents and skills are developed by training for a wide range of events.