Actually it could be one's poop as I think it is the last thing one's body physically lets go of when one dies.....
Sorry, just being sarcastic as I think the question is generally pointless the way it's phrased as it relates to Bike Forums. I'm thinking maybe the OP really meant something like.... "Which of the bikes that you have that you most prize"??....this being Bike Forums, afterall......
To answer that question, it would be my Vitus Carbone, of course...but I only have two bikes to pick from!
Chombi