Most of the genjutsu shown in the series has been cancelled in one way or the other.
Sakura, Gai, and Kakashi used unseal jutsus to cancel Kabuto's sleep genjutsu. Naruto used an unseal jutsu against Itachi's finger genjutsu thing. Shikamaru and Kurenai used self-inflicted pain to get out of genjutsus. Uchihas and Hyugas can use doujutsu to see through genjutsus. Then finally, there's always the option of plain cleverness to beat a genjutsu, such as Shikamaru beating Kin or Naruto's team beating those rain genin.

Really, the only successful genjutsu I've seen so far would be some bunshin maneuvers Sakura pulled way back in the day, and of course Itachi's Tsukuyomi.

If a genjutsu succeeds, then yes it's potentially more powerful than the other two. Unfortunately though, if it fails, then its pretty much completely worthless.

In the case of tai and ninjutsus, there is no solid black and white like that.