1) The longest lived was a PDP11/34A. Made in the late 70s or early 80s, it was still running when I sold it in 2005. Did a couple of component-level repairs, and I reckon there's every chance that it still runs today. Not sure if it counts as "personal" though. I have a polycarbonate Macbook from 2007 still going strong, so I guess that makes the answer "Apple".
2) Self-built. From pretty mainstream components, Ryzen 5600X, Asus motherboard. It should last me at least 10 years, with maybe a GPU upgrade along the way.