What spirits or entities have you had the most intense communication and interactions with?

For me the most intense interactions I ever had would be Succubi, though I have never kept one, but I did summon them on two occasions... Proper methods, etc... And well, without sharing too much, wow. The energy was great. Communication though was a 0/10 - Interaction was a 6.5/10 I think

Looks like you should be keeping an ubi or two ...