MECH + MECH + AG + AG (Assault Gun - Stugs)
MECH + MECH + TD + TD (Tank Destroyer - Jagdpanzers)
note: you can basically add Self-Propelled Artillery, S.P. Rocket Artillery, or Armored Cars (Scouts) to the above combinations without spoiling the CA benefit.
It's fun to see the MECH icon alongside your infantry and Armored divisions on the map. I like seeing the icon, probably like you do too.