So some say that nothing is ever really bolted down, eventually you'll get bored of them and want to move on. I think it's harder for us with small collections (1 to 5 pins). Larger collections make it easier to not get bored.
Metallica is my only keeper, we'll never sell it unless to upgrade to a Premium/LE. My wife won't let me sell it and after 1.5 years it still hasn't gotten old. Still hunting for a pin #2 that will also become a keeper.
Name the pins that will never leave your collection.