Low Cal vs. Low Carb
Fad diets are not the answer, but as many people strive to find lifelong diet changes they can stick to, the inevitable question becomes whether to reduce the calories, or to reduce the carbohydrates.
The answer is relatively simple, actually. Low calorie is a generally the better option for life long commitment. Because most dieticians and nutritionists don't recommend deprivation of any one food group, a low calorie option allows you to experience a variety of foods - just in smaller portions and less calorie/fat options. Calorie deficit between input and output is needed to lose weight. An equal in/out calorie balance is needed for weight maintenance. As such, counting your calories allows you to monitor this more clearly.
The exception to this rule of thumb is if you're suffering from certain medical problems. Diabetes, some gastrointestinal issues, certain syndromes, or high triglycerides are all instances in which medical professionals generally advise patients to cut back on carbs.
Of course, even if you're eating a carb-heavy diet, you'll want to be sure you're eating whole grain carbohydrates. Refined carbohydrates have very little nutritional content, and do not help in weight loss.