@vxma: I agree to what you say except this:
If I have 4 archer s and 3 warriors, I do not look as strong as if I had 6 warriors and 2 archers.
You do, but it's close though.
I could have even more for the 110 shields, say 7 warriors and 2 archers.
This is true and it proves that your general point is correct: if it is about "appearing to be strong", warriors are better value for your shields than archers.
Let's do the calculations. This article in the War academy
Study of Inner Workings of Military Advisor explains that the formulae used by the military advisor to determine you as strong/weak/average is this (if I read the article correctly):
Units Strength = Hitpoints * (1.5* AttackPoints + 1 * DefensePoints ) + 0.175 * Bombard Points
Your strength is the sum of this for all units you have. We then have (assuming regulars):
reg archer = 3(1.5*2 + 1) + 0.175 = 12.175
reg warrior = 3(1.5*1 + 1) + 0 = 7.5
4 reg archers + 3 reg warriors = 48.7 + 22.5 = 71.2
2 reg archers + 6 reg warriors = 24.35 + 45 = 69.35
2 reg archers + 7 reg warriors = 24.35 + 52.5= 76.85
For veterans we have:
vet archer = 4(1.5*2 + 1) + 0.175 = 16.175
vet warrior = 4(1.5*1 + 1) + 0 = 10
4 vet archers + 3 vet warriors = 64.7 + 30 = 94.7
2 vet archers + 6 vet warriors = 32.35 + 60 = 92.35
2 vet archers + 7 vet warriors = 32.35 + 70 = 102.35
According to these formulas, an archer does not count as twice as strong as a warrior. But it does cost twice the shields. So in that respect the best value you get for your shields is by building warriors only. And if your goal is to prevent war only (which is often the case in the early game) that is exactly what you should do.