I meant: depending on the civilizations,
military tech can give you : nothing / +2str / a unit / a building (often useless) / an equipement.
as most civilization do not have 4 units on the military tech tree, at least 1-2 lines will have NO units … and in each line, at most 1 tech out of 4 has a unit.
I usually find that only the military strategy line is useful : buildings are useful / you get the +2 str / you get warrior district and wonders.
then, for the others, unless you have a unit on the line, they are often not so useful, tier 2 tech (archery / bronze...) give nothing to you: it is a "lost tech": roughly it works only as an entry-price before being able to research tier 3 tech which sometimes give you +2, but if you don't have any recon unit, nothing on the recon line is useful : so 4 techs for getting only 2 (+2). if I have tier 2, I'll research tier 3 and the +2str makes it worth it (save for luirchips). otherwise, having to get a tier 2 and a tier 3 only for the +2 is not useful
tier 4 gives +2 so if you researched tier 3, often you take it even if you get nothing else.
tier 5 can give +2 or powerful units or nothing... but if you have the powerful unit there.. it is often the only unit of that line : you have to research a whole expensive tree for the last, very expensive tech.
equipement in military tech is often useless as you get more interesting equiment in other ways: vampiric sword, or dragon leather armor which are found in guilds...Etc
equipements are not differentiated enough IMO. Main effect are often too close (save for vampiric sword), while diffenciating effect is to small:
comparatively, the arcane tech line is more interesting: you get a unit on any odd tech : 1 out of 2, you get useful buildings every techs, you get useful equipements every techs.
In fact: magi guild added to the arcane line and (almost) did not take anything from it.
In comparison, hunter guild / mining guild / esus guild took things from the military techs.
that said, I think some civilian techs are not expensive enough.
but at the same time, as you need guilds... making them too expensive might be bothersome.
Here comes some auto-brainstorming:
Re-training buildings:
They seem limited: +15% up to 15 xp… or +20% up to 10.. then: so I have +35% until 10 xp, and +15% from 10 to 15 ??? not so useful: remember that 10 xp is level 2, and 15 xp is half of level 3.. ;and that until level 4 … I canno't chose a promotion
Accordingly I never use them, save for the free "cash xp" : +3 to archery units …
I think it would be better to have them at : +25% up to 15 more xp, every building adding to each other. So training ground + bowyer + archery tower + war academy + barracks could for example bring any archery line units to 10+15+15+15 = 55 xp… and then it becomes useful: it is level 5 or 6 depending on traits (+maybe have the initial training level be higher?).
Maybe, if you change only that on training building you could make do without most of the rambling ideas I mentioned above.