There are plenty of reasons we part ways with a car we loved. But if all of those were removed from the equation, which car would you take a second lap with? I've had many classic cars. They were all special to me for various reasons, but if I had to choose just one tho, it would be my '63 split window Corvette.
(I've tried to buy it back twice, no luck. It will take an estate sale)

 

My '67 Tempest Sprint convertible. Reverse died and I junked it. It did need all sorts of work and I was still very young and broke. That OHC 6 with the 4 barrel and the Hurst 4-speed was a true delight.

 

My 1969 Dodge Charger R/T. 440 Magnum, 4 speed Hemi transmission, Dana rear and factory installed rear shoulder belts.
Due to an injury and lack of funds I couldn't finish the restoration.

 

One of the intrinsic values of ownership is understanding the notion that the “journey is the destination.” Pride of ownership and being able to say " I had one of those" is part of that value.
(I would place my SRT high on the list if/when it is sold due to it's rarity and performance)