Is it more important to count calories or carbohydrates, and then does sugar content matter?

Sugar content matters a lot, we cut simple carbs because they are easily processed into sugar.
As to the carbs / calories, you should try to keep carbs down to about 50g per day and calories to about 800 to get the best results.

All foods contain energy measured in calories when it is released. Bill gives good advice. As an example I have now lost 40 pounds by keeping my sugars to <30 gm/day and my average calorie intake was 850 for 11 weeks my BMI is in the normal range now. Sugars are densely packed calorie packages refined sugars being some of the worst.

It depends on your goals.

If you are trying to follow the blood sugar diet because you are attempting to induce diabetic remission based on the underlying research, the diet is 800 calories coming from a variety of nutrient dense mediterranean style foods, including “good” carbs. No specific carb limit is recommended by the author – and if you follow the meal plan in the book, the carb count varies considerably from day to day.

For those of us who are diabetic, many of us are uncomfortable eating enough carbs to elevate our blood glucose above a certain level – and some of the recipes here push the limit. Although I seem to be able to tolerate more now, at the start I could not tolerate more than 20 in any 3 hour period. So that is my personal cap – but it is not one imposed by the BSD.

If you are not diabetic (or pre-diabetic or have another condition tied to carb intake), there is no medical reason to limit your carbs. Limiting your calories to 800 will cause you to lose weight, even if 100% of those calories come from carbs. But eating that many carbs wouldn’t be consistent with the diet, which encourages a well-balanced mixture of foods (including “good” carbs). In addition, many people find that limiting carbs and eating relatively more fat make it easier to stick to eating only 800 calories. Trial and error has caused many people who post here to adopt a cap of 50 grams as a quantity that works well for them.