Vs. PTRS & SU76 (spam or no spam) you really don't want weak vehicles / armor on the field. They just gonna get obliterated easily. You want infantry superiority, support guns, and vehicles that survive on the field.
Get the usual Volks & Spios, into LeIG, back that up with Raketen to ambush the SU76. Offmap infantry can help a lot, like Panzerfuessiliers or Jaeger Light Infantry - the latter unlocks infiltration nades which can be very useful vs. Maxims if your opponent doesn't pay too much attention.
Lategame the usual, go T2 and Stuka for more AI, or T3 for something more heavily armored like a Panther. JP4 also helps to dish out dps on range vs. armor, map dependant though.
Thanks!