There actually is no solid answer to this question because my parents raised me a classics pirate (Arrrrg!). I used to had a massive NES collection on the computer at all times, so it could have been any NES game that started with A.
Nowadays I like to emulate games that are just impossible to find elsewhere, like the rest of the Adventures of Lolo games that were under the title Eggerland, or anything I can get my hands on on Archive.org for PC.
I have a bit of a rule against pirating anything you can still purchase elsewhere. (For a reasonable price, Ebay does not usually have reasonable prices.)