I play World of Warcraft, it doesn't do to get overly attached to somrthing you'll replace weeks later.
But if I had to choose something it'd be the Obsidian Edged Blade from old-school Molten Core. I was after that sword for so long, the few times it did drop I was cruelly outrolled, and then on the night I managed to lay my hands on it, I got the Eye of Sulfuras, main component in crafting the legendary Sulfuras.
... I was mildly annoyed.