well personally as an athlete, i would rather win worlds. :D but even if i was a level 1-4 athlete, i'd still say, i'd rather win worlds.
as a coach though, i think having successful lower levels/open 5 would be more important/better. they are the building blocks of the program, and will one day be those level 5 athletes, so it's important to start at your roots. not just that but it gives the program a good image overall. i personally do not like seeing gyms who have kick butt level 5s, and then their lower levels are left unnoticed. a gym is a program for a reason. it is comprised of multiple teams, not just the one/ones with the most talent.