We have used Oral B for years, and after trying the more expensive models, now we buy the most basic model we can find.
The major difference we have found is actually in the toothbrush heads. The basic bristle brushes wear out and becomes dog eared quickly. The more expensive ones with some form of plastic (eg plaque removal) built in with the bristles lasts many times longer.
By the way, they all have a low battery indicator… they stop.
IMHO, the batteries in their major weakness for at least three reasons. Firstly, there is no manufacture date on the packaging, so when you buy a new toothbrush you have no idea how long it has been in storage. Some toothbrushes have only lasted us six months before needing to be in the charger every day. This could be because either they have been in storage a LONG time, or perhaps the batteries are poor quality.
Secondly, the batteries are not replaceable. If the toothbrush is in good condition but the batteries won’t hold charge, why should you have to throw out an expensive electric toothbrush? The batteries are soldered in, and I have not been able to find any available replacement batteries.
Finally, I am not sure what sort of batteries they use in them, but they are not good quality in terms of how long they hold charge, and how little use it takes to flatten them.