I personally think they are. I use one and the stains have pretty much disappeared on my front teeth. I drink a lot of coffee and smoked for years and so far, the electric is the only thing that has helped.
I am currently a dental hygiene student. I have seen a huge reduction of the plaque accumulation when my patients are switching to electric toothbrushes. Remember choosing the soft bristle brush head for electric toothbrush is very important too.
I got 2.....oral-b, and sonicare....but not flouride tooth paste=poison...read the label....haven't used it since early 2000's....baking soda, sea salt, holistic options,
no national brands again....
My dentist told me it actually depends on the brand, oral b is a good one but expensive. The most expensive ones are usually the most effective, others can actually cause more damage instead to your gums or not reach the gunk well enough.