For me, it’s an electric toothbrush. It doesn’t matter if you go with Sonicare or Oral-B, once you start using an electric toothbrush, regular toothbrushes don’t ever feel like they clean your teeth properly. The smooth plaque-free top layer of your teeth that you can feel after using an electric toothbrush can’t be replicated with a regular toothbrush.
I have an older style Breville Stand Mixer. It has attachments like a dough hook, beaters, scrapers, etc. I thought I’d never use it. But! It sits on the bench (must be there for ease of access), and the amount of times I use it is astounding.