In reply to Rob Naylor:
I have a MacBook Pro Classic (2012). So long as you max out the RAM and install a fast SSD, it's still a good machine for many tasks – even things like Lightroom (although newer Macs will of course be faster). It will run the latest version of MacOS fine and is very fast in general operation. The great thing about the Classic is that you can install a second hard drive alongside the SSD, if you remove the optical drive. For me, this was more important than a Retina screen. Unlike the Retina MacBook Pros, you can also easily replace the battery and many of the other components yourself. That's why I went for the 2012.
Must stress that the SSD upgrade is *essential*. It's only fast if you run the system from an SSD. MacOS is slow as a dog from a spinning hard drive, no matter how fast the processor.
EDIT: Forgot to add, don't get a used Mac laptop with a discrete graphics card. They are notorious for failing. Integrated graphics (like on the 2012) are less powerful but far more reliable.
Post edited at 10:01