none, the one u play better.
There are many sets up for black and for each one, several (many) ways to play it...
The idea is not playing the best (theory doesnt know which it is), but playing the move where u feel comfortable.
U don't know which one suits to u?
Well like most openings u learn :
- watch some games played by champions, and see if u like it.
- play it to see if u feel ok with it (sometimes i see openings i find great : i play it and i understand it is not my taste...).
After 9.h3, which one is the best: 9....Na5, 9....Bb7, 9...Nb8?