While it's not a SCSI model, I suspect that the scanner on my LaserJet 1100a, circa 1997 - which I still use at least weekly - has more staying power than many scanners made available in the last 10 or 20 years. I still use it with SANE on a modern laptop running Fedora.

The last released driver for this scanner was for Windows 2000. That driver works fine on Windows XP, but not on Windows Vista or higher. Luckily, as a Linux user, hplip supports the scanner out of the box. When I was still a Windows user, I'd run NT4 in a virtual machine, pass the parallel port through, then share a folder between the local machine and the VM.

The fact that it's a parallel scanner presented its own set of archaic problems, like "what mode do I put the parallel port in?". Luckily, since upgrading to a machine without a parallel port, I've let that be the responsibility of a JetDirect 300x, which exposes the scanner as an IP network device. I've had significantly fewer problems since adopting that setup.

The page count on the scanner is around 25,000, and still holding strong.