I don't like a buck to be too mean, nor too "sweet." A mean buck is just dangerous, but a buck that's too sweet tends to get pushy and treats you like a herd member...that's dangerous, too. A buck that's just plain ol' scared of you and won't let you touch him with a 10' pole can be a PITA, too..
With our new buck, I'm shooting for a healthy mutual respect so I can scratch his head when I bring him grain, but still retain the ability to run him off by acting like I've just lost my mind (ie., waving my arms while stomping toward him, yelling "GIT GIT GIT!!"...or whatever )