Characters for Motion Design have a different feel than that of entertainment. 

When the characters purpose is to sell a product is important to have that character be friendly and look like the audience. This means that diversity of all kinds is important, size, gender, age, ability must be considered as you develop people that fit the brand you would be working for.

This can vary right now as you are developing a portfolio. Look into the industry to see what market you would like to aim at. You may also look at what is missing in the industry and what your particular perspective can bring to the industry.

You will need to start with the information first and not the character. What are you trying to say and how can this person you design say it best?