What kind of horse would be good for me?

If I were you, I would be looking for the right horse and the breed is a bonus, unless of course you want a specific breed. You are better off getting a good horse that is not one specific breed than saying, for example, 'I'm only getting a palomino thoroughbred' and it turns out to be a crap horse but it is a palomino thoroughbred. Any breed or mix of horse can excell at showing, its a matter of finding that horse.