Hello, I'm just level 15 for now but I am beginning to have lots of companions, so I decided I will need help to put them in a right order. Here they are, in order:
Subodai, level 13 Horse Warrior; Ratbeard, level 13 Rat Commander; Old Screech, level 13 Undead Witchdoctor; Milo Graytail, level 13 Rat Brigand; Bonnie Anne, level 12 Fox Sharpshooter; Sarah Steel, level 12 Mouse Fencer; I forgot his name, level 15 Monquistan Spearman; I also forgot his name, level 16 Crazy Monquistan (with a crossbow).
I found that over time of leveling companions up some that i had in the top rows when i was lower level didn't no longer fit in the top rows.I have all 22 companions i own at lvl 50-53 i have changed top row lineup a few dozen times just depending on what im doing
Just play with them and figure out how you wish to set them factoring in the world your in,levels,and how your playstyle is.