Because research costs of troops are really high and takes a long time as levels increase, it is more valuable to focus on a particular set of troops for both war, farming and castle defense.

 - **Farming:** So it is generally accepted that barbarian, archer, goblin, wall breaker, minion, giant + healing, rage are good for farming.  

 - **Defense:** Archer, wizard, dragon, minion are good for castle defense.

 - **War:** All dark elixir troops, pekka, dragon, healer, balloon, wizard, wall breaker, giant, archer + all spells are good for war.

While we don't have too many choices for defense, we have [a lot of tactics][1] that can be used on offense with mixing different troop and spell combos. Various types of barch, tank + dps, tank + healer, all air etc..

I am looking to only upgrade and only train a minimum amount of troops but still be very effective in all aspects & stages of the game. Theorycraft based answers would be appreciated or Town Hall9+ players with experience.



> So what is the best attack compositions to focus on general?


  [1]: http://www.clashofclans-tools.com/Attack-Strategies-Guide