One of the best is 'Grasscutter'. It's a story full of adventure and honor as Usagi gets involved in a quest related to a powerful sword. The art in this story is also amazing, really bringing the feudal Japanese setting to life.
Love is a very common theme. Since Usagi and Mamoru have a strong romantic connection in the original story, fanfictions often expand on their love, like how they overcome obstacles to be together.
One great 'usagi x mamoru fanfic' is 'A Starry Encounter'. It beautifully portrays their relationship with vivid descriptions of their interactions. The author does an amazing job of capturing their chemistry.
In usagi x misaki fanfic, one characteristic is the focus on their relationship development. It often starts from their first encounter and gradually shows how their feelings for each other grow. Another characteristic is the creation of a unique world for them. For example, the setting might be a peaceful small town or a big bustling city. Also, the fanfic usually emphasizes their individual personalities. Usagi might be depicted as gentle and caring, while Misaki could be shown as strong - willed yet with a soft heart inside.
One possible scenario in a Seiya and Usagi fanfiction could be that Seiya, being a strong and confident character, helps Usagi face a new and particularly difficult enemy. Seiya's different approach to fighting compared to the Sailor Scouts might offer a fresh perspective to Usagi, leading to her growth as a Sailor Moon. They could start off as rivals in a sense, but gradually develop a deep understanding and friendship that could potentially turn into something more romantic over time.
In another scenario, Usagi and Mamoru could be at a ball. They dance gracefully together, lost in each other's eyes. After the ball, they take a stroll along the beach. The sound of the waves crashing against the shore sets a romantic mood. They hold hands tightly and exchange sweet nothings, reaffirming their love for each other.