Hard to say, really, and depends on how we define childhood. ;)
NES days: Probably Legend of Zelda (the original), and Paperboy. Bubble Bobble too.
SNES: Super Mario Kart, Legend of Zelda: A Link to the Past, Final Fantasy 6 (has been a constant love since) ... Secret of Mana... god there's quite a few.
PS: FF7, FF9, Star Ocean: The Second Story... the list can go on and on. And then I stopped being a teenager. Alas. XD