For me it was my 2003 BMW K1200RS. After 50,000 glorious miles over 3 wonderful years I dumped it for a Goldwing. I'm still flabbered I could be that misguided (a nice way of saying 'stupid'). Then I doubled down and replaced the Goldwing with a Ducati, a day rider if there ever was one.
When I decided to undertake a 8,000+ mile cross country trip my tiny 400 lb Ducati would not be the pony of choice for any but the most iron of butts, I needed a stallion, indeed that long gone K1200RS would have been perfect. So I shopped for an equivalent, but with a better dealer network enroute than offered by BMW, I've always liked BMW's but I'm a realist. Last January I found a new left-over 2009 Concours 14 that delivers the same riding experience; it's power to weight ratio, ergos, and handling are surprisingly close to that K-12, so I pulled the trigger. In 25 days the kickstand goes up.