I like strategy games that allow you to design your own units such as Warzone 2100 where you select different components to get different functionality or Endless Space 2 where you pick a ship hull type and then assign different modules to adjust the combat stats or add special abilities. The production cost of the unit changes with your selections in whatever the base game currency is and/or requirements for specific resources.
This gives the player the freedom to adjust their forces to fit their play style, their economic situation or to accomplish specific objectives or strategies. It also breaks the rock/paper/scissors aspects of unit combat in more simplistic games and creates far more complex unit interactions, and the potential to win with clever design rather than just numbers of units.
Have you played Antichamber?