At present, probably my grinder. I routinely use it to grind up coffee beans, seeds and nuts. Of course that's not counting the computer I use or my phone.
It varies. Something like my coffee grinder gets used two or three times a day but not for very long at a time. Some of my power tools can go days or sometimes weeks without being used but then get used extensively for a few days in a row, only to get cleaned off and put back in their storage bags for another few weeks.