My personal experience: Electric toothbrush and razor. I especially hate the razors, you can replace the head, they could last a lifetime, but the battery is practically dead after two years. Toothbrushes are improving, the last one has 3 years of service and still work ok.
I'm using an Oral-B electric toothbrush from 2009. The (non-replaceable) battery needs to be charged about every 3-5 days now, which is not a problem because it sits in its charging stand every night.
My wife bought some cheap electric toothbrush that runs on AA batteries, which can be rechargeable and have a lifespan independent of the gadget.
