My favorite pieces are those which are works of art in themselves, and have been beaten up and become attached to memories, preferably along the full adventures' gamut of joy and distress.
My maps, which I can stare at for hours and are still usable anytime I want to. Google earth is also a fun way to do this, but so far I haven't gotten that wet/burned/stained/sun-faded, so it doesn't count.
My paddle, a wood XY Meany bent-shaft out of Atikokan, Ontario. Not the lightest by far, but a sheer joy of a tool to hold and use.
Whatever tarp I can find myself under, especially when I most need to. Not enough of those memories being made lately.