Party Quests

Henesys PQ, I've never quite liked. The best EXP is in the Bonus and no one does it.
Kerning PQ, if you can finish in less than 8 minutes or so (I think), or you hog Stage 1 (assuming you can easily kill Ligators) or Bonus (with one person per platform), then you should get better EXP than training.

Hogging stage 1 is way better than anywhere else. The ligators give 120 exp each, which is pretty damn good even if the map isn't the best for training. It does consume pots for weaker party members, though.