What to recommend that my friends and yuri disciple haven't covered yet...

Itoshi Koishi
5 Seconds Before a Witch Falls in Love and the sequel oneshot, 5 Seconds Before Falling in Love with a Witch
Fuzoroi no Renri
Your True Color
Dekisokonai no Himegimi-tachi/Failed Princesses
Himawari-san/Miss Sunflower
Philia to Eros no Aida
Houkago/After School
The Miko's Words and the Witch's Incantations
Chatting at the Amber Teahouse
Everything Zanka's done, Oh Dear Lord There Are So Many Gay Maids

And a personal favorite that isn't yuri, Itoshi no Kana