It's a Pentium 3 PC from around 2002 and it was my sister's. It has an Abit VH6-T board and originally a Celeron 600, 256MB RAM and Geforce MX200, a few years later it was upgraded with a Pentium 933 and a Radeon 8500LE. Later our dad got it who wasn't that tech savvy, but wanted to learn how to use a computer because of work. That was around the later-mid-2000s, around 2007 or so. Then went to the bottom of a wardrobe for the next couple of years. When I moved out I took it and still have it with unchanged specs and the same Windows XP install I did for my father back in the day, though the optical drive is faulty.
The second longest was my previous daily driver I bought in February 2009. A Gigabyte GA-MA78GM-S2H board with Athlon X2 5050e, 4GB RAM and Radeon HD4670. It was upgraded to a Phenom II X3 720 and HD5770 around 2012 and a Phenom T X6 1055T and HD7850 around 2014-2015, and at some point around the Phenom X3 upgrade another 4GB RAM was added. I used this PC until September 2019 and sold it in December the same year. That's a little over 10 years. I kept the case and the 3.5" memory card reader though which I still use for my XP nostalgia PC. Sometimes I regret selling it. I didn't get that much for a PC that old and it would also make a great XP nostalgia PC. It's probably in a landfill by now.
My current daily driver is No.4 on the list with 5 years of service life barely a year behind the PC I used in my high school years, but I will upgrade it with a Ryzen 7 5700, another 16GB RAM and an RX7600 and continue using it for a few more years. I can easily see it taking the No.2 spot.