Have you taken a look at our character meal photo & information thread? This will give you an idea of what characters to expect:
http://www.disboards.com/showthread.php?t=2234435
I prefer breakfast. Now, to be fair, I have not had the Goofy's dinner in years, and it has changed a bit since then. I've done the breakfast countless times. It wasn't even the fault of Goofy's that I didn't care for dinner in the past - I just wasn't hungry when I went there so nothing appealed to me.

Goofy's has a large buffet, with lots of choices. Here is a link to a page from Disneynerd420's Trip Report, in which he posted some excellent photos of the Goofy's Kitchen breakfast buffet offerings (scroll all the way down the page, as the photos are in two different posts - #338 and #339):
http://www.disboards.com/showthread....268157&page=23
Goofy's Kitchen has the widest variety of food and there could be anywhere from 4 to 8 characters roaming around at one time, depending on if it is a shift switch or whatever. The characters who are commonly seen are Chip, Dale, Goofy, Pluto, Baloo, Minnie, Max, Princesses (Belle, Jasmine, Aurora), Alice and the Mad Hatter, soemtimes Captain Hook and the Genie, or any combination of those - it really is kind of a rotating cast of classic Disney characters. I used to think that the more interesting characters showed up at night, but apparently it just depends on whoever is available that day or night to come by, so you might see the same exact ones in the morning and at ngiht, or you may get a whole new crew!