For me, it's a bidet toilet seat. I bought one that didn't really fit as well as I hoped, so now I am shopping for a v2 based on experience. I don't want to live without one going forward. That's for sure.
Not really a gadget but tools in my car, countless times people or even I’ve needed them and because I carry them around with me in my car it’s been a life saver and a small electric drill to make it easier instead of using a rachet or screw driver