Who was Jack closer to.......Micki or Ryan?
I would say Ryan.
shareI agree, I think he saw Ryan as the son he never had. I have never really watched much of season 3 but I do remember the episode after the Ryan character is gone and how Micki cleans everything up, even turning the area where Ryan used to sleep into s sitting area and Jack is the only one who speak up and say something, If I remember right he asks if this is her way of dealing with what happened.
"These pretzels are making me thirsty!"
I don't know I think he loved them both equally. I know Jack and Ryan were particularly protective of Miki and we saw Ryan going to extreme measures to bring Micki back when she died.
Of course Jack did have that son of his who died so he might have transferred some of that to Ryan.