Always enjoyed Mac OS 9 on my old PowerMac G4 but when I moved up to the PowerMac G5 running Mac OS 9 was no longer an option. There is no denying OS X is superior but there was something about Mac OS 9 that made it special.
Stumbled upon a great tutorial on Youtube that allows PPC emulation of Mac OS 9.0.4 on a piece of software called Sheepshaverhttps://www.youtube.com/watch?v=XQAf7GII9NY
This works on OS X (Intel) 10.4.11 Tiger to OS X 10.11.6 El Capitan (doesn't work on macOS Sierra)
I currently have it running on OS X 10.6.8 Snow Leopard flawlessly.
Mac OS 7 and 8 can also be emulatedhttps://winworldpc.com/product/mac-os-9/90