We all use the Philips Sonicare Flexplus. (about 120$) It's a big difference from the ones that are 30 bucks or so. My mother's workplace (Pediatric/Adult General/Ortho dentist) all promote this toothbrush.
Sonicare does up to 30,000 brushstrokes per minute. Versus a cheaper one that may do 5,000. This makes a big difference.
They have lithium ion batteries. Which keep the toothbrush running for a good 2-3 years. Spending 100 bucks on this toothbrush is about 5 bucks a month.
It also has the UV sanitizer that reduces the amount of germs you're brushing with. It's also got three different settings, and two timed modes. AND they come with a 2 year warranty. None of the cheap ones come with warranties.