Esperanto culture is full of interesting concepts: gufujo, aligatorejo, la bambo… Is there one country that has influenced Esperanto culture in particular?
Given the three examples gufujo, aligatorejo and la bambo, I'd have to say Germany has had the greatest influence, because of the Internacia Seminario (IS), their annual youth event (1957-2009). For certain, gufujo was founded during the IS according to the Esperanto Wikipedia's entry on Gufujo. Even though La Bambo originated in the IJK in Belgium in 1982, the IS was more renowned for people dancing it for hours. Even though, the origins of the Aligatorejo are unknown, it was frequently an event at the IS cementing it into Esperanto meeting culture.
As for literature, a surprising amount has come from Hungary from famous authors such as Julio Baghy and Kálmán Kalocsay. Having said that, an overwhelming amount of Esperanto literature is produced in Europe compared with the rest of the world.
Most Esperanto music is produced by artists and bands in Europe and Brazil. If I had to choose the most influential country that would have to be France considering that's where the Esperanto label Vinilkosmo is based. Only these regions currently have dense enough groups of Esperanto speakers or meetings to make it easy to meet up and form bands to produce high-quality music.