What are the advantages of being a farmer?

The farmer class has 2 main advantages. You will gather faster and be able to unlock class cards that let you gather more resources. And you will gain a depot protection level that will stop enemies taking all of your resources if they attack you. The level increases as you level up.

The down side is you will not be as strong or fast when attacking others but if you are more of an afk or peaceful grinding player then the farmer is the best option.