The Legend of Zelda is hands down my favorite series, with my favorite of them being Majora's Mask. That may be due to nostalgia.
Earthbound however is not due to nostalgia. I got it on the Virtual Console recently and loved it.
But as much as it pains me to say, my number one game is Undertale. It has made me contemplate life, feel, and laugh. It's made me feel happy, challenged, and terrible. It's an amazing game that I would recommend to anyone.