What's worse in terms of nutritional value, sugar, fats or carbs? Is there a simple answer?

I don't think there is a simple answer unfortunately. I find that if you look at the origin of the food.. and the form in which is was given to us by nature, is usually the healthiest for us. Sugar is pretty much the same thing as carbs, the only difference in the food is how fast or slow our body breaks it down into glucose, or sugar.
Fats in their natural form, words like "extra-virgin", cold pressed, organic are usually the closest to the way nature made it. Too much or too little fat can be unhealthy.

As far as nutritional value, in relation to energy, Carbs and Protein provide about the amount of energy per gram(4kcal), whereas fat is better as far an energy value (9 kcal/gr), and keeps us satiated longer (hungry less).

You want to avoid the things that man has done to manipulate food.. processing, refining, bleaching, ...even pasteurizing, microwaving, and homogenizing ... usually fortified with stuff that was stripped out.. the stuff nature intended us to have as part of a natural, fresh, mostly plant based diet.

Good question. Thanks for posting.
Doc Rob