An NPO "Furusato kaiki shien center (Support center of moving to rural regions)" researched their customers' impression of their destinations. The center asked their customers where they would like to move to, if they start their rural lives. 2885 of customers answered, and the most popular prefecture was Yamanashi.
The below is the top 10 list of them.
Central Japan seems to be popular.
Source is Furusato kaiki shien center.