Oh… that’s a huge question. It’s been a long time now. I have used these in various projects for a lot of engineering, research, home networks, and embedded projects. I almost always run them headless over a serial console then SSH in for management.
RPi 1 - my son used it recently for the RCA TV out
RPi 2B
RPi 3A+
RPi 3B+
RPi Zero
RPi Zero W
RPi 4B+
Beagle Bone Black - I ran a pair of these as TOR relays for years. They were tanks.
NanoPi NEO-LTS
NanoPi NEO Air-LTS - The current one in service is an OctoPi server for my 3D printer
Orange Pi 5 (I got one of the 32GB ones! - currently a Plex server with an external SSD and onboard M.2)
Orange Pi Zero2
C.H.I.P. Computer - this BTW was one of the best little hacking computers. It was phenomenal to setup and run over the OTG USB console
Bannana Pi (original) - It was great because it had a SATA port so we used them to back network Linux installs for smart home kits.
I do a ton of other work with embedded microcontrollers too. Lots of ATMega and SAMD boards, plus a bunch of ESP 8266/32 variants.