Nakiri
The nakiri-bocho is highly suited to cutting vegetables generally and leafy vegetables in particular. It's all in the name - 'na' means leaf in Japanese, 'kiri' refers to the cut.
Most nakiri knives feature a tall, thin, double-bevel blade. Minimal curvature equals clean cutting on the board with a variety of Japanese cutting techniques. If your diet includes a lot of vegetables then a nakiri is a great investment.