Utility infantry for scouting. Neither JLI, Fuss, or Fallsch are supposed to be the core of your army/assault force. JLI are just OKW Pathfinders, Fallsch are insanely expensive while being quite fragile, and Fuss are just slightly better 6 man Volks with no shrek.
They are supposed to augment your force so you can adapt, none are supposed to be your bread and butter like shocks, but they do give you the utility of conscripts which OKW lacks.
Whaaat??? They are melting infantry. 20 kills for Pathfinder is someting but for Jaeger? Thery are amazing. Keep them behind Volks and watch how they are sniping.
Fallsch are fragile the the dps... Just get behind green cover. And again they are expesinve cause they spawn from any buidling and have amazing weapons already.
Fuss are great as well. Fuss+Med truck without Flakbase is quite good strat.
And by the way, Ostheer also has call in infantry and tanks.