I haven't read much of Monster, but it definitely holds the idea of the value of life. Being a famous heart surgeon, the main character constantly has to make choices which life needs to be saved. If he kneels to the kindness of his heart however... he is bound to get destroyed by his greedy superiors.
- Liar Game
One of my personal favorites (see signature). I thought after Death Note I would be the last of the stereotypical "intelligent manga" for me but this convinced me that there are others out there. The Liar Game throws Nao, a woman who is far too trust worthy for her own good, into a game of cheats and lies. Two people are given 100 million yen, but at the end of the month, this money has to be returned. However, you can steal your enemy's cash as well! Meaning what ever money you steal, becomes your profit at the end of the month.. but also your opponent's debt. This is a battle of intelligence and psychology!