[MMM]

Personally the best time is Late March to April when cherry blossoms are blooming, but it is difficult to schedule a trip exactly for that.

August festival times are also great, but it is very hot and humid.

The end of the year is also good, as there are many New Year's events at temples, but it is also very cold.

Kyoto is a good example of Japan's "four seasons". Every season shows a different face, so you will see a different one every season you go.