What is the best Kindle e-reader?

This is the most comfortable Kindle to hold yet. At just 4.6oz, it feels very light and because the back isn't flat (about 1/3 of one side is thicker), it feels better to hold in one hand as the weight is mostly along that edge (the center of gravity is held right in your one hand). You also don't need to worry about where you put your thumb as much - the 'spine' has ample room to rest your thumb.