Gee there's so many ways to go that it will be mind boggleing; And then on top of it you'll have everyones own personal preferences that will confuse you even more. They all have merit; The problem is your going to a photo market, where all kinds of crap can show up in the form of cameras with problems. Not a good thing, cause getting some cameras repaired can cost more then what their worth. At least get a return policy. If they won't give one, go to the next table.
By now you should have investigated somewhat the features of different cameras, or at least compared ones you've seen to others. Maybe a friend had a Nikon, Canon, Minolta Or Olympus you've handled and were somewhat taken with it. Go from there and research the camera online, and make a determination after checking Ebay as to what is available, lenses and accessories and check the backtalk as to what people have said about the camera in various forums. It will be in the forums where you will find the problems with any particular brand and model.
Each brand has cameras that were good or bad in someway. Research is what it is all about. Don't make a mistake without arming yourself with knowledge; And don't be in a hurry. Ebay can be just as cheap as a photo fair.