Thief sub or main?

[Sirch]

Hey, Latly I changed my job from warrior to thief mostly because it just got plain boring, I am having fun so far with thief and I was thinking about the future with it, So far as a second job I have thought maybe use Ninja, but I wondered shoud I keep Thief as my main or Ninja? What is best? and is Ninja a good advanced class to pick? Sorry about asking so much on my first post.

[Tokitoki]

Theres a whole tpic about the THF/NIN job