If Shinjuku-gyoen is my favorite park in Tokyo, Sankei-en 三渓園 is my favorite one in Kanagawa. It was a private garden owned by a family of silk traders one hundred years ago. Sankei Hara was the family member who first bought the land. He loved Japanese gardens and architecture so much that he decided to design the garden by himself, he also brought traditional wood houses that he loved from all over Japan.
If you visit it early during a weekday it is a very quiet place with areas where the forest and the Japanese style houses will be for you and nobody else. I recommend it to everyone who complains about being tired of visiting temples and shrines filled with tourists when traveling around Japan for the first time.