I was a Sinclair man for much of the early phase of the original home computing so I came late to the Atari party. My first Atari (around 1986-87) was therefore a 520STFM, which I still have. Originally 512K RAM, it acquired a further 2MB of RAM not long after I bought it.
Around 2001, I got talking to a guy at work who was looking for a basic PC and discovered that he had an almost unused Atari 1040 so I went home and built the best PC I could throw together from the parts I had lying around and the next day, offered it to him as a direct swap for the Atari, which he agreed to. When I finally set eyes on the 'new' ST, it turned out to be a 1040 Ste, still in pristine battleship grey livery as it had never been exposed to the sun for any length of time.
I tested it and then mothballed it in a dark place, and continued using my original STFM which was already dark orange and beyond cosmetic redemption. After about 15 years the STFM failed (temporarily). When I got the 1040 Ste out of storage to use while I was fixing the original machine, it worked for about half an hour and then froze up: That turned out to be due to the PLCC sockets, particularly the one for the CPU, not making good contact, and it was only properly and permanently repaired when I replaced the sockets. I also took the opportunity to upgrade its 1MB of memory to 4MB - unlike the STFM the RAM was in SIMM form factor and easily replaced.
As things stand, both machines are still in working order. The old STFM workhorse is still used quite a bit: The Ste is back in dark storage to preserve its colour.