Oral b pro 1, 2 or 3. They use the same motor and batteries as their most expensive ones, which is really the only bit that matters. Everything else is just gimmicks to justify the price… Bluetooth connections and other bullshit.
And don’t bother with official heads either. Generics work fine. Just remember to change them often.
I’m on a Poco right now. The hardware is great, so once you remove as many invasive built in apps as you can you’ve got yourself a great deal.
Look up how to use adb bridge to remove apps. Most are safe to remove, SOME are not. There are lists online that will tell you which is which for your make and model.