I find it odd that nobody has picked Keet or session.

bossrosschild

ssl + irc.  oldest and best internet chat, and still obscure enough that normies will never be able to use it.

cecil

двух пиринговая система общения... 
я тебе пишу в сигнал...
ты мне отвичаешь в телеграм

Please indicate which of the chat apps listed below is best for privacy?

Please expound your reasoning further in the comments if you will.