One of the spreadsheets has the modifiers for ground combat for each combination of attacher strategy and defender strategy. The modifiers aren't that big. Most of them are 100 -- meaning no modifier -- and the best are only 120 -- meaning +20% for the attacker and -20% for the defender.
With so many options for the defencer to choose, your chance of getting a good modifier is small. So overwhelming numbers are much more important than strategy. (Massive overkill is not wasteful, as more of your troops will live to fight again.)
Three attacker strategies, however, have no downside: Feint, Ruse, and Surprise. For these the modifier is never less than 100.
It would be nice if some clever modder realized Moo3's goal of meaningful and realistic strategic options (assuming the AI is up to it); but in the meantime attack with force and use one of the three 'safe' stratgies.
Caveat: Your milage may vary depending on what mods you are using.