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.
A Vitamix blender. Most reliable blender I’ve ever used and so many things you can make in it. Smoothies, nut butters, you can even cook soups in them.
They are on the expensive side, but the worst model refurbished is still well worth having and goes on sale from time to time.