Neither. One isn't more important than the other. You get the weaknesses of both. The body is responsible for capturing the light that the lens focuses. If the lens isn't sharp enough resolution of the body doesn't matter. Similarly, if the resolution of the body is low, then sharpness of the lens doesn't matter beyond a certain point. Lens speed impacts low light performance, but so does the sensor size and the ISO capabilities of the camera body.
One could argue the lens is more important in defining the shot since it defines the focal length and depth of field, but the body is responsible for instructing the lens how to focus (if using AF) and making the exposure determinations as well as being capable of capturing the image.
There are situations where it makes more sense to invest in one than the other, but that is highly situational.
In general though, you want the camera body that meets your needs with the best quality lens you can put on it. If the lens would have to be really bad though, it might be worth a body that doesn't quite measure up to what you'd like to be able to have a decent lens instead. You are more likely to be able to put a cap on the needs of your body than your lens though.