I love the corn bread at Cape May Cafe. The best part is that it's unlimited. I'm sure some people may find it too sweet, but as an Iowa girl, I love my sweet corn and sweet corn bread (in my opinion, the best corn bread is made with real Iowa sweet corn, or at the very least, real sweet corn).
The corn bread at Whispering Canyon is pretty good, and I like the corn bread served with the Mom's Night Out meals at Pop Century.
I have found that a lot of the corn bread options at WDW seem to be rather sweet. As I indicated above, that's no problem for me, as I prefer it sweet, but if you don't like sweet corn bread, you might want to take my opinions with a very large grain of salt.
Also, as the PP suggested, it might be a good idea (if you really love corn bread) to take some mix home with you. The Jiffy mix isn't bad, but I personally prefer the Betty Crocker mix if you can find it. Either variety makes a great corn bread, especially if you add real corn kernels to the mix!