It's more a complex thing that just saying good art is better than writing or vice versa. You need both. And it is more than just a good wrtier and good artist working on something together. Both parties need to have a sense of fun and like this is really cool. To me when i work with my artist, I look at it as a partnership between both.  Sure, I might be the creator of the universe and have a general idea on the epic storyline and a general idea of what they should look and feel like.

Beyond that though I leave a lot up to my artist. She should feel like an equal part in the creation. And as writer, it is my job to give her the freedom and the challenge of doing different locales and what things look like.  To make sure that she doesn't get bored doing it.