If I have all orange heroes and all well upgraded. What is the best combination of heroes in the same..

It depends on the orange hero. The normal setup is fighter, vehicle, shooter. fighters being for defense, vehicle for load and shooter for shooting. look at the skill of each of your orange hero. For example, War Hound I use for Vehicles. Also try to unlock the awakening skill as soon as possible, it is awesome on any hero that has it.