Both need to be done. Teeth require maintenance to last your life time. Daily brushing/flossing is necessary to remove the plaque that caused tooth decay. Any toothbrush used appropriately with suffice. Dental cleanings are performed 1-3 times/yr for most people to remove the hardened plaque(tarter) that causes gum disease. Your toothbrush cannot remove tarter.
Similar. I have patients that get great results with both techniqes. The most important aspect of brushing is to do it 3 times daily. If you have a dexterity problem the electric brush may help you reach difficult areas. Some patients prefer to use a higher tech device; and get better results because of their higher compliance rate.