I think reading in general makes you a better, more rounded person. With that said, I would have to say that
Twilight is the book I have to go with. The reason? Because this book is what got me reading daily again - something I hadn't done since grade school. We had to bring home these book logs and fill them up each month, then bring them back for little prizes or certificates.
With all of the chaos that surrounded
Twilight, I finally gave in after a few friends had read it and thought to myself "What on earth is the big deal surrounding a silly vampire series?". As soon as I began to read, I knew.