Ultrasonic vs. nebulizing (waterless) diffusers — which is better?

Ultrasonic diffusers mix essential oil with water and emit a cool mist; they're cheaper, double as light humidifiers, and use less oil. Nebulizing or cold-air diffusers atomize undiluted oil for a stronger, longer-throw scent and can cover much larger areas, but they burn through oil faster and cost significantly more. Reviewers across the pool generally recommend ultrasonic for single rooms and bedrooms, and waterless for whole-home or commercial spaces.