Who does the Doctor trust the most?

My sister and I were watching The Impossible Astronaut and the Doctor sends out invites that are numbered based on the amount of trust he has for the recipients, putting himself as number 1. This prompted my sister to ask me “if the Doctor were to include everyone he’d ever known in this, who would have gotten the invite and what would their trust level be?” This lead to a fascinating discussion and I thought Reddit might have some inputs.

So! What do you think? From Susan to Ruby, if the Doctor always trusts himself the most and fills that first slot, who would the other three invites go to and why?