I have a thing with Japanese castles and I try to visit as many different as possible.
So far the Matsumoto castle has been my favorite castle. It totally feels like a fortress, so no enemy could enter it. Even inside it's very dark and you can finally possibilities to protect this castle from one of the winodws.
You should keep in mind, that the stairs are really steep sometimes. It can get hard to reach the top.
But also from the outside this castle with the landscape around is so pretty, that I plan to visit it again on my next trip.