It's hard to ignore Zelda.
Rampage I actually have on Master System, must've played it over 30 times in as many years.
I've spend awful amount of hours on Breakout clones (including making levels for one). I've finished some version of Arkanoid too.
But my vote goes to Dragon Quest as a major ancestor of JRPGs, a genre very dear to me.
And I think the first game is better than FF1; in fact the Nes DQs are generally better than Nes FFs.