awesome topic, i happen to be wearing it today!
my true and only grail would have to be the the first watch i ever bought with my own money. saved and saved for it. it was the beginning of a wonderful journey. without this one there would be no others and no passion for watches.
its not the most expensive watch, but to me it is my grail.
1994 Rolex Daytona would never ever part with it.
watches will come and go, but this one will stay with me and my bloodline forever.