I foresee the tech trees doing as well as they did in Shogun 2, i.e. everyone just pumps points in the military tree because that's what's important in Total War and the strategy side of it has always been an afterthought at best.
Que?
Going for economic bonuses and spamming the much more efficient Ashigaru was the way to play. Yari Wall was almost brokenly overpowered if attacked from the front (which you can always count on the AI to do) and generals + light cav/yari cav was strong enough to work as the hammer to your hammer and anvil. Also Yari cav hard countered much, much stronger cav due to being spears vs. swords.
Off the top of my head the only important military line techs to get fairly quickly was the tech for fire arrows (because it was literally a cheat button for sieges and naval combat, causing almost instant explosions) and the encampment (which provided unit buffs ontop of the buffs you got from the blacksmith/bowmaker to make even Ashigaru into strong units).
There's also the fact that the way realm divide worked meant you were incentivized to wait a bit before triggering it to power up your economy with how the food bonus worked to stack more and more wealth into your settlements every turn. That meant getting those food techs.
EDIT: Also, opening the game for the first time in 2 years, I remember that Generals had a trait for increasing military tech research speed. So in the mid to late game when you had a bunch of leveled up generals you could have much higher military tech rate and really speed through the tree to whatever you want. The Civilian techs didn't really have this bonus, only agents and very late tier buildings gave it and those were far harder to attain.
