Shisui, it's been stated his EMS allows him to make the victim do anything he wishes.
Also his sharingan allows him to use high level genjutsu, although I'm not sure what they are but apparently he ended up forcing Danzo to use Izanagi.
1. He can control every Bijju Neg Diff.
2. He controlled a perfect Jinchuriki for years!
3. He was about the complete the Mugen Tsukuyomi.
4. He could Control Kurama from a very long distance whilst having a death match against strongest person of that era, Yondaime!
5. Only person to have used the Perfect Izanagi!
6. No one dared to put him under any type of genjutsu because it's utterly futile U_U
NO one comes close to Obito in genjutsu, by feats or by hype U_U
Itachi Tsukuyomi (& other genjutsu) canonly , but Shisui's Kotoamatsukami is the best genjutsu.
Shisui uses the single best genjutsu , but Itachi is the best at genjutsu.
The best Genjutsu is KotoAmatsumami, Tsukuyomi, and Infinite Tsukuyomi. The best genjutsu users are Uchiha Itachi, Uchiha Shisui and Uchiha Sasuke. The best counter/reflection genjutsu users are Sasuke and Itachi. nuf said
Misconception between all, let me clear, Shisui have strongest genjutsu while Itachi is strongest genjutsu user, kaguya is not here cuz she uses juubi to uses Mugen tsukuyomi, while other two here uses their own chakra, i hope i've made it clear