Maat is hard on any job but the easiest i have had so far is Ninja. I soled it first time as a 66 Nin. The fight was rather smooth, take his shadows down and debuff him. Although he used Mijin Gakure then immediately used Asuran Fist, I still had around 1/4th hp (200-250). After that the fight was smooth after I put shadows back up and used my vile elixir.
Actually the easiest fight is Thief if it is your first Maat fight. You don't even have to beat him, just steal from him. This isn't the case if you've fought Maat with any other job though.