Jericho all the way. He would be my first pick and then i would get Dogmeat to be more of a backup.
Will Jericho remain with you even if your Karma reverts to the opposite spectrum? I was thinking of playing evil just to get him and then becoming good afterwards. I just don't want to waste time trying to get him if he is just going to leave me right after the change.
As this is only my first play-through right now, I have to say Charon is the best. Especially considering how he'll join you no matter how nice or vile you are.