I find that I am most comfortable playing characters around my age as well.

The advantage I see to playing older characters is that they have more accomplishments. It's not very convincing to be a teenager who solved world hunger, took collage for ten years, and built a hundred homes. An older character allows for that, as they had more time to do stuff with their life. 

Younger characters are cool because they are still figuring themselves out. As a result, they can have a view of the world that doesn't line up with what everyone else sees. There are many experiences that they haven't felt yet, like loving a stranger or traveling the world. Younger characters feel these experiences more intensely because they haven't done them.