Which is better: fasting on Mondays and Thursdays, or fasting three days each month?

Fasting on Mondays and Thursdays is better and carries more reward, because these are the days when deeds are presented to Allah the Almighty. The Prophet, peace and blessings be upon him, used to fast on these days and liked his deeds to be presented while he was fasting. Fasting the three days (of the white days) is included within that.