I am not sure if anyone even cares anymore about such mundane information. However, if you do, I found a comparison of nutritional data that may interest you.
Calories Fat(grams) %Calories from fat
Burger King's Whopper w/cheese 720 46 58
McDonalds Qtr Pounder w/cheese 520 29 50
Wendy's Big Bacon Classic 640 36 51
As you can see, all of them are unhealthy in terms of fat to total calorie ration, but McDonalds does fare marginally best in that category.
Obviously, the best solution to this contentious issue is a knowledgable consumer, who, armed with nutritional data, will order a salad or a grilled chicken breast instead of one of the above fat burgers.
Incidentally, the above information was published in Cooking Light magazine, July/August 1996.