Actually, this is a trick question.
The answer is that you should be both contented and to have the desire for more.
You see, most people, when asked this question, will tend to think either or. There are some things in life that you have to make a choice but in this case, it is perfectly fine to have both.
Unless you are living in the Wudang Mountains, it is impractical to be too contented in the society we are living in. On the other hand, too much desire will always make us feel insufficient and deprived.
Therefore, the best way is to always be contented, yet also have the drive to work towards achieving more in terms of our desire. This way, you will feel happy, yet ensuring that you live your life to the fullest.