KidLove said:

I would like to know which knowledge has the best bang for your buck in reference to troop strength. Should you max out the big 6 in the military tree first. Should you steadily upgrade hero, military and invader tree. I am just curious how should you prioritize you knowledge for troop strength. 

There are many different opinions on this but first you need to decide what you're using your troops for. Are you most interested in attacking or defending in times like when you're farming? With that said many of the most knowledgeable players believe that the hero skills - Enemy Troop Defense, Enemy Troop Offense and Enemy Troop Health - will give you the best mathematical advantage. 

Also most of the better fighters concentrate on only one or two troops types. Put most of your knowledge toward their improvement and train far more of those than others.