I don't know, I'd probably put WHM/BLM before SMN any day.
Like others said already, WHMs brought a whole umbral era upon us, and now a mere handful of BLMs scare the current WHMs shitless because they fear these few BLMs could bring another umbral era again.
SMN's power ends at a part of the power a real primal has, and even all 3 primals summoned at once is nothing but a minor disturbance for the planet right now. Even Bahamut, in all his full power might (not the mere piece of his power a SMN has), was basically the softest umbral era Hydealyn ever saw, no wiped out civilizations and nearly full recovery after only 5 years.

The Jobquests of WHM/BLM highlight the fact that both their powers are limitless and our characters are basically only holding ourselves back all the time because of the great destruction it would bring otherwise.

Now for the melees:
I'd put DRG, WAR and MNK higher on the list than PLD, BRD and NIN. The latter are just normal fighters with normal bodies and basically no supernatural stuff going on. of course, that doesn't mean one can't win against another in a fight and I'd expect plenty of ninjas to be able to kill any mage before they could cast a spell, but if we talk raw maximum power here, it's something like:
1. WHM, BLM (potential for unlimited destruction)
2. SMN (primal power, still far above anything a normal human being could do)
3. DRG (consumed dragon's power, one of the stongest non-godly species)
4. WAR, MNK (normal humans but with a bit of a supernatural touch)
5. PLD, BRD, NIN (normal fighters who honed their bodies to the maximum)

I left out the new jobs because I haven't seen most of their Jobquests yet