My standard post marius army consists of
-4 Praetorian/Legionary Calvary
-4 Archer Auxilla
-4 Legionary Chorts
-2 Praetorian Cohorts
-2 Urban Cohorts
-2 Heavy Onagers
-2 Arcani
The cohorts can be interchangable. Also if I can I prefer Cretan Archers over Archer Auxilla.