In my opinion it's not what is better. You need to ventilate a attic to keep moisture from damaging you home. and keeping air circulating up in the summer will also help keep it cooler. I a ridge and soffit vents are enough then there is no necessary reason for a power vent. My current home had the ridge and soffit and I felt my attic was not as well ventilated a wanted so I added 4 basic roof vents. I also when with a medium gray roof when re-roofing instead of the black that was originally on the home. (The lighter the less heat in the attic from the sun) This will make a dramatic temp difference in the attic in the summer. I don't feel with these changes a power vent would benefit me and it would be a possible source of noise and maintenance. however I have installed the on homes without enough attic ventilation and herd of the electric bill dropping even know the power vent to wattage to run because it helped the A/C load by keeping the attic cooler.