My favorites are, in order,

1) Machinist - Fun as hell, and I love all the support options!
2) Ninja - Mudra fix makes it so fluid!
3) Dragoon - Because Aerial hip drops. Too much Mario Party.
4) Astrologian - Because I get to read your fortune! Unfortunately, you have bad luck today. No balance for you. :3
5) Scholar - I like devising strategies, even if this job is more about dps then actually being a competent healer.