When you are faced with casting a voice actor for an animated production, there are certain things you have to know before you proceed. You can't just decide to make a production and then go hire a voice actor and hope everything turns out all right. Even if you have done a lot of work on the script, it is not going to come together unless you cast the right people for the spots. No matter how good the lines are, if the voice actor does not deliver them properly, then your vision is not going to be realized.
You may not even know what a voice actor delivering the lines properly entails. That's all right, if you are willing to turn over some of the creative process to the voice actor. But you have to know enough about it to cast a voice actor you know will do a good job. That means you understand what kind of character you are casting for, and that you consider all of the variables, like accent, before you look for someone to fill the role.
Is your character original and complex? Is he a rogue with a heart of gold and many shades to his personality? A character like that, even in an animated production, is going to need a voice actor that can pull off the complexities of the character. That means you are going to have to understand those complexities so that you can explain them to the voice actor