Some people like to buy and sell. Their tastes change or they don't seem to get too attached to things. I'm kind of the opposite in that it pains me to sell anything off even if I don't wear it. I guess I'm just a hoarder at heart.
I have quite a few that will never leave my collection. My Sinn U1 comes to mind as well as my Dornbluth 99.0, Doxa 600t, Ocean7 LM-1, UTS 500, Stowa Prodiver and some iteration of the Blackwater.
What are the ones in your collection that you will never part with?