Since you said you've already tried SMN, I assume that means your ACN/SMN/SCH is level 30+ and your CNJ/WHM is at least 15+. If not, at the very least, you'll want them both at level 15 so you can unlock the jobs at level 30.

As Rikku said, it'd be best to try them out to see what suits you. WHM and BLM were my favorite classes pre-Heavensward, however you might find SCH more interesting instead. It's all personal preference.