As a dealer of Japanese woodblock prints and shunga in particular I have come accross numerous striking and evocative designs. 
The following 10 shunga designs appeal to me and are in no typical order. These prints I saw in books, on auctions and in private collections.

An extraordinary and extreme scene from Shigenobu's Willow Storm -series (late 1820s) involving a Chinese Couple. The man with his plait curled on top of his shaven head is extracting fluid from the woman's vagina. In his book Sex and the Floating World Timon Screech remarks that Keisai Eisen wrote that such fluids were used as an aphrodisiac and rubbed onto the male's genitals before intercourse. (Illustrated in Japanese Erotic Fantasies - C. Uhlenbeck and M. Winkel on p.177, Ill.65b)

he sixth plate in 'The Fashionable Lusty Maneemon' series (c.1770) by Harunobu depicts an intriguing scene in the open air with a peasant girl being taken from behind by a man wearing a mask. 
Her parents are watching while the man claims he is a descendant of Inari, the god of rice. Maneemon also called 'Miniature Man' or 'Imitation Man' who's the main protagonist in this series is a comic mythical character who sits relaxed under a tree on his straw hat. (Illustrated in Japanese Erotic Prints, Shunga by Harunobu & Koryusai - Inge Klompmakers on p.65)

A scene with a totally nude couple in a soixante-neuf position in a perfectly balanced composition. This print is from Hokusai's most celebrated oban series Fukujuso (The Adonis Plant) and is so distinguishing because of the large scale of the portrayed figures. Some shunga lovers call this image the 'Egg'. 
(Illustrated in Vol.23 of The Complete Ukiyo-e Shunga - R. Lane)

A striking depicition of a Dutch captain having intercourse with a beautiful courtesan. They are watched (by the viewer) through a window of a Nagasaki brothel. 
Behind them on a small table an incense burns in a vessel. This specific detail is on a lot of shunga designs depiciting this theme and it is said this use of incense burning by courtesans was to drive away the smell of their Western clients. 
The long fingernails of the Dutchman are also a striking detail. 
Dutch women were not allowed to live in Nagasaki but Japanese courtesans were permitted to enter the compounds. Eiri's Models of Calligraphy was inspired by Utamaro's Poem of the Pillow which also has a Dutch couple. 
(Illustrated in Vol.24 of The Complete Ukiyo-e Shunga - R. Lane)

Last but definitely not least the most famous of all shunga designs best known as The Dream of the Fisherman's Wife from Hokusai's Young Pine Saplings (Kinoe no komatsu) -series. A depiction of an abalone diver abandoned in an ecstatic embrace with two octopuses. For a long time collectors and scholars thought this infinitely fascinating scene to be a rape scene but this has been refuted by Danielle Talerico who discovered that an Edo audience would have associated the image with the legend of Tamatori. Also the text in the image indicates the mutual satisfaction between all involved protagonists.