Let me start by saying I'm not a hard core user. I've owned both.
I agree with Steve, they are both excellent knives in their own right.
The Mad Dogs I've had leaned toward the fighting style. If I was ever going to be in a serious fight and depended upon a knife to get me out, a MD Panther would definitely be my choice. I simply dropped my ATAK Thing from waist high, hit my calf muscle, and managed to put the point more than an inch into my leg. Now that's a sharp, perfect shaped, fighting blade in my opinion. The MD fighters, and especially the shape of the handles, are made for fast and furious situations.
If I was stuck out in the woods and needed a knife to depend upon, I would hope I'd have my Busse with me. The weight and style of my Natural Outlaw just makes you want to whack away with it, just cause you can and it likes it. I didn't really like the Busse E-handles at first. Totally different than Mad Dog's. But they grew on me, and after using them they really started to make sense.
I haven't owned the hard use style knives of Kevin, i.e. the ATAK, so I'm not doing a apples to apples comparison here, just trying to give you some additional insight.
Before anyone makes up his mind they should hold and evaluate both. You just can't decide by looking at your computer screen.
Mark