Both have their strengths and their flaws. I will explain better:Priest
Strengths: High in respect, trustfull, powerfull magic depending on the god, considered the leader of the group, wealthy, even kings can be with one.
Flaws: Must pray all the time, sacrifices to the god, depending on the god he/she must have a standar typeof behavior(for example, the priest of Ares, is brutal, hideous and loves bloodshed, not to mention, wickedly evil.), has the opponent god's hate.Druid
Strengths: Extremely powerfull, doesnt rely on gods to spellcast, respectfull, trusted amongst the nature's creatures, great natural abilities like shapeshift.
Flaws: Not trustworthy by people, close community among the druids, other druids observe anything you do.
Depends on your playstyle, in greece the priestesses were mighty powerfull inside city states you know? While out in the wilds the druids were top dog. In war though the warriors obviously rocked the house. Note: Athenian warriors were sailors, it was the Athenian navy that defeated Persia's sea forces.
Actualy Beautifull Lie, that happen 1000 years after where we begin.
At our times, Athenians had little army and more philosophers, their major army were the kings army, which were about 3000 people and the priestesses of Athena, about 200