For Misaki's crew, anyone of the Last Blossom models would be a good edition. Right now those include Yamaziko and Oiran. The Ten Thunder Brothers are a pretty solid addition to most crews too, even though they don't have Last Blossom anymore. Thunder Archers are solid as well.
For Mei Feng's crew, I would consider getting Metal Gamin. Being as she can take up to 4 Foundry models that are out of faction, Metal Gamin are a good choice. If you want a big beatstick to go along with them, a Rail Golem would be nice too, although the damage output from Mei Feng and Kang together is already pretty good.
The Shadow Effigy comes out soon too. Definitely get that, as it would benefit both crews greatly.
Good luck!