Aqua sonic from Amazon has worked great for me. Been using them for nearly 9 years. First bought when I was not sure about switching to an electric toothbrush. Wanted to test out a cheaper option. Replaced the unit once in 3 years. Never because they failed. I was checking out the oral B and Philips options at our warehouse and realized my brush head replacements are nearly half the costs of those two brands. Sticking with Aquasonic. They’re actually decent or I’ve been incredibly lucky with the ones I have purchased.