Kitchen -
Most used - Instapot. We have an air fryer attachment so we frequently find ourselves air frying chicken, then swapping out and making rice. Thinking about getting a separate air fryer to eliminate the extra step.
Least used - Convection oven feature on the microwave. We thought this would be handy for small meals so we don't have to use the full oven. Nope - actually takes longer. We don't use it at all.