Strictly early I think either Persian leader is very strong. Cyrus is a superb warmonger. Darius has the traits to take advantage of any early warmongering. Pity 1 can't suceed the other like in RL. The UB is ok, the UU is IMO the best early rush unit. Starting techs - Agriculture gives your workers something useful to do whilst you tech AH and the Wheel, Hunting - well the scouts useful for locating horses and your early targets.