Replying to this on my 2009 MacBook (2 Ghz Core 2 Duo, 4GB RAM, 500GB spinning rust drive). Starting up involves rather a lot of that spinning beachball, but it's mostly OK in use. Will finally be retired and replaced with something with Apple Silicon, perhaps launching as soon as WWDC…
Main system is a 2010 Mac Pro 5,1, bought end of 2019 to replace the dead 2009 4,1 I bought in 2013 (it befuddled repair technicians). 32GB RAM, startup SATA SSD on PCIe card (Mojave), 3TB HD (Mac data), 500GB SSD (Windows 10), Radeon RX580 8GB, USB 3.0 card. Old, but gold. Still in use is my Mac Pro 1,1 bought new in 2006, hooked up to a 2007 BenQ monitor. Waiting for the AS Mac Pro or a slightly-less-extraordinarily priced 7,1.
And a lot of the peripherals are old too. I still use an original (beige, and somewhat yellowing) Microsoft Intellimouse Optical (my first one died after a year or two, this one I think is 17 or 18 years old....). My HP Deskjet 959C dates from 2001, original cartridges no longer seem to be widely available but remanufactured ones are no problem. Scanner's an Epson Perfection V500. Most recent speaker purchases: two Creative Labs Inspire 5700 sets (2003) from eBay. Bought the first a couple of years back, it packed up after about 18 months. Bought another, that broke too, sadly...they sounded great when they worked. I'll be buying something Not Creative to replace them.
Prior to the 1,1 I had a G4 (Mirrored Drive Doors, dual gig). The 'Wind Tunnel' machine (got a lot quieter with the Apple replacement PSU).