Title says it all.
Never played the first MOTHER game, but the second and third are two of my favourite games of all time!
MOTHER 2 (aka EarthBound) is thrilling, funny, and trippy! [spoiler]The final boss[/spoiler] is pure nightmare fuel, but being scared just gives me a rush of adrenaline!
MOTHER 3, on the other hand, is so sad. It was the first video game that made me cry. But that's what I love so much about it.