Mei Feng: Mei Feng, Kang, Forgeling, 3 Rail Workers -> Explosive Material, Heavy Metal and Bayou Engineering are honestly all good to get. I would recommend that order.
Mah Tucket: Mah Tucket, The Little Lass, Trixiebelle, 3 Bayou Bushwackers -> I would get Rooster Riders and Wierd Science
Lord Cooper: Lord Cooper, Model 9, Artemis, Ullr, 3 Runaways -> I would personally get the Malisaurus Rex, it is good with Cooper 1 and a must if they ever get Cooper 2. Second pick would probably be the ES starter box. Bellhop Porter is also really good with Cooper, but sadly comes with 2 less needed models.
Lady Justice: Lady Justice, The Judge, Scales of Justice, 3 Death Marshals -> I actually don't know too much about Lady J, but I think I would get Six Feet Under mostly for the Lone Marshall. Pale Rider and Guild Steward could also be decent pickups.
Nekima: Nekima, Blood Hunter, 2 Mature Nephilim, 2 Young Nephilim -> Blood Ritual for sure and then Corrupted Hounds are also very solid after they recently got buffed.
Viktorias: 2 Viktoria Chambers, Vanessa Chambers, 3 Ronin -> Not too knowledgable about Vics, but I feel like Loyalty to Coin is a solid box to get and Hodgepodge Fate can also be good in the right situation.
Seamus: Seamus, Copycat Killer, Madame Sybelle, 3 Rotten Belles -> I would definitely get High Society and I am actually not too sure what else to suggest. Hats off comes with White Rabbit Co. that can be really good, but it is an expensive box to get for 1 model and 1 alternative master.
Misaki: Misaki, Shang, Ototo, 3 Torakage -> I would probably get Silent Strike and Karmic Debt