What do you own that you wouldn't replace with a perfect copy?

Three questions, and only the first one really matters. Answer one or answer all three. There are no wrong answers, I am genuinely just curious.

Not the most expensive thing you own. The one where a flawless duplicate would be worth less to you than the original.

What makes a thing worth keeping? Pick the one that matters most.
When you buy something you will keep, how do you decide?