Final Fantasy Tactics.
I go on and on about it a lot, but it really formed me a lot as I am mow because of it's influence on me as a child.
Other than that, probanly Super Mario RPG: Legend of the Seven Stars, the game that inspired me to learn to read (I beat it before I could read. X3) and the Legend of Zelda: a Link to the Past. Ialways got to Ganon before I got stuck; I didn't know about the Fat/Ugly/Great Fairy or the Fairy Sword or the Silver/Light Arrows.