I think it is Gaea Foundation. It was awesome :D But it would be strange for me, to have box with cosmetics always with me, when i am a guy.
I think that Balzac would be useful, but it depends on the users potential.
In my opinion the most useful Teigus would be:
Spectator, read peoples minds
Mastema, never need to walk again.
Lionelle, healing factor.
Perfector if you are a doctor, writter or artist.
without particullar order.
About Gaea Foundation, the teigu always disappears when it is use, so if you use the teigu before leaving your house or use it without anyone looking, no one will find it weird
What do you think?