Buuuuuuuuuuuuuuuut, with no art at all, it's still not a comic... and you can still have a comic without text, the images can tell the (writen) story on their own. :wink:
You need both writing and art equally, although not in equal balance.
Well of course you need both. I don't think anyone is suggesting that either can be done away with completely :) I mean, do away with the art and you no longer have a comic :)
That said, you can (and should) use the artwork to tell part of the story, but you shouldn't use the dialog to reveal something about the art. Therefor there is writing in the dialog and the artwork, but there is only artwork in the artwork, not the dialog.
(and none of that crap about writing being an art. Of course it is. I'm using artwork to refer specifically to drawn works here ;) )
So you can say that the writing is more important, because it is a part of the whole comic, whereas the artwork is only in the visual aspect. Of course you can also say that the artwork is more important, because you can do everything with it.
Now that I've said that, I'm starting to lean back towards the artwork being more important, because of how much of the writing it can do for you :)