For me it was 2 bikes
First my GS1000S Suzuki I had when I was 21, not sure if it is any consolation, but it was nicked, so I didn't really make the decision to sell

That was a great do anything bike, the ultimate UJM.
The other was my first enduro bike for green laneing, my KDX200 Kawasaki. Good sized tank, great tractable bottom end / mid range torque, good suspension & seat. I sold it for more serious off road machines, but they never matched the versatility and useabilty of the KDX.
Other bikes like the 400 SuperDream Honda I didn't loose any sleep when I sold that
