Great points, Cat-Man.
Yes, I think any consideration for this honor must include an artist who regularly drew covers and interiors. AFAIK, Schomburg never drew interiors, so he would have to be excluded.
I would exclude newspaper comic artists. Since most of Eisner's best work was done for newspapers, that probably excludes him.
By "best overall" I was thinking of some one who drew covers and interiors as well as a variety of genres: adventure, humor, sci-fi, super-heroes.
Personally, I thought Wood was great in humor, adventure, horror, sci-fi, war. But he arrived a bit late. His style only came into maturity in 1951.