I started CNJ last night and during the first quest, I went from Lv.1 to Lv.7 by fulfilling the quest requirements, a F.A.T.E that spawned round me and the 1-10 hunting log.
Daily Roulette is also good as you receive Exp bonuses, tomes and gil. Also, the bonus for completing a Guildhest for the first time. Or, grab a few friends, summon your Chocobo and F.A.T.E grind to get Exp for you both.
For DoH classes, Leves are awesome. Took my GSM from Lv.20 to Lv.34 by doing Leves in Ul'dah. HQ turn ins = huge Exp!