I always pass them on to family but this time I'm keeping my intel MBP as a backup and secondary device. New machine is for work + some personal stuff. Old machine is for compatibility with old software, dual booting, workshop stuff with lots of dust, etc.
Edit: to expand on this, if you're moving your primary rig from Intel to Apple Silicon for the first time you should keep your Intel machine around untouched for a good while if you have the option, especially if you're like me and are still running a very old 10.X version of macOS. You might run into issues with both the new silicon platform AND OS.