Simply a matter of how long you want to be down there!
Fall is going to be roughly about 4 months and Fall Advantage will be about 7ish months.
If you aren't sure you want to be down there that long apply for Fall and you can always extend if you get accepted and stay down there for the 7 or 8 months! You can actually extend your program up to a full year! Same process and same requirements for both programs!
Good luck!