I like you have a fair few from the Pi 1 all the way to the Pi 4.
I still have a few in use:
Raspberry Pi 4 - this is running with a PoE hat and is both my Unifi controller and DNS server for my network
Raspberry Pi 3 - this is running a Raspberry Pi camera and motioneye software as part of my CCTV system. In all honesty the camera is no good for night time (its outdoors) but until I can be bothered to research and find the right camera for my needs it does the job.
Raspberry Pi 2 - this is acting as a print server for an old non-wireless and non-network laser printer I still use.
I have a few more that are going spare - like you a lot of the stuff I used to do on Pis is now done on my Unraid server though I still like to keep network functions e.g DNS on a seperate machine so if I have to reboot the Unraid server or do any hardware work on it, the network is still functional.