the first armor set you unlock is still beast too i used it from time to time , it give you over like 50% physical resist still really good.....dont know about being the best but , full kraken armor with the lvl 9 sword of poseidon , really good because you can activate L1+▲ more often which means you can have extra elemental damage more often and its also guard breaking and causes knock back meaning you leave it while open for a Ice maelstrom attack or L1+■ attack.
might actuly try it with war armor of poseidon and see what the extra ele power does to it .
Level 30 Zeus. I use the God armor, and the Maul. I find that with well timed dodges, the maul's knockback lets me go toe to toe with quite a few players when I have no mana... like at the start of nearly every freaking game.