I made my previous post early in morning just before work and didn't have any time explain further what I meant by it. Truth is that I have put some thought into the military GBs issue and I think I got a pretty good and balanced solution for it. But problem is, it might be considered tad too complex or confusing.
It is similar to what Martynius suggested in terms that I propse static increases intead of percentage ones. But they come individual for different unit types. And there is a kicker I will address later on.
For example Bronze age Statue of Zeus would give a few more attack and defense bonuses to different unit types at every level-up, until finally at lvl 10 it would give out the following bonuses:
Light melee: +4A, +4D (Spearman 7/7 increases to 11/11)
Short range: +4A, +2D (Slinger 7/3 increases to 11/5)
Fast units: +4A, +3D (Horseman 6/5 increases to 10/8)
Heavy melee: +3A, +5D (Warrior 6/9 increases to 9/14)
Long range: +2A, +1D (Stone thrower 3/2 increases to 5/3)
This would effectively mean a player with bronze age armies and lvl10 statue of zeus has his army increased on average from 7+7+7+3+6+5+6+9+3+2=55 to 11+11...+3=87, an increase of 87/55=1.58 ala 58% (compared to 50% it would be now).
Yet player with CA units and lvl 10 Zeus would have the follwing increase with those static bonuses:
Ranger 35/35 to 39/39
Musketeer 30/18 to 34/20
Dragoon 28/40 to 32/43
Greneider 28/40 to 31/45
Field Gun 14/6 to 16/7
This would be an effective stats increase from 274 to 306, a 11.7% increase in military effectiveness(2.5 months ago I would have taken it without heartbeat lol).
My proposed Cath of Aachen static bonuses when finally maxed at lvl10 are the following:
LM: +7A,+7D
SR: +8A, +4D
F: +6A, +7D
HM: +6A, +9D
LR: +4A, +2D
Lvl 10 Aachen would that way increase EMA total stats from 101 to to 161, an increase 59.4%. For comparing, same Aachen would increase CA stats from 274 to 334, an increase of 21.9%.
My proposed stats for lvl10 del Monte:
LM: +14A+14D
SR: +14A+7D
F: +12A+14D
HM: +12A+17D
LR: +7A+3D
LMA units stats would increase that way from 199 to 313. An increase of 57.3%. For comparison it would increase CA stats by 41.6%. A CA army with all 3 military GBs maxed would have a total bonus of 75.2% instead of 150% it gets now. But remember CA has no military GB. If it did, the number would be little bigger(if del monte was CA building not LMA, then it would be stronger and total bonus for 3 GBs would be near 90% for example).
There is one major drawback with static bonuses though. Obviously they can not be allowed to be added to weaker units than the units the GB is from. Imagine a spearman if he would be allowed to get all, including EMA and CA static bonuses. It would be a 32/32 unit that costs nothing and takes 20 seconds to train lol. So the much needed change would be, that military GBs only have effect to units from same or more advanced ages.
This is the part I'm afraid may sound confusing to some players, but logic wise it will make sense quick. Your dim-witted primitive units just don't understand the new wonders of the world lol and get no bonus from it. Besides static bonuses otherwise don't work(only alternetive is creating specific bonuses for Every spefic unit from every age for every level lol). For example a player with 3 military GBs all at lvl10 would get only zeus and aachen bonuses to his trebs, only zeus bonus to his archers and all 3 bonuses to his rangers. It may sound tad unfair intially, but if you make the math, all 3 of those units actually get not too different % amount of total bonus compared to the original units.
Anyways with this same would need to happen to defensive GBs, static bonuses and whatnot.