Dirt cheap (calculated in gold/man) and top stats are the two things that realms should strive for.
Yes, as you said, many things only consider troop number. But in many wars, none of these things will be done. And if all you plan on doing is fighting, you are much better off with a small army of elite troops than a horde of cheap troops.
Frankly, from my experience what you choose for your units has less of an effect than the # of units you have. If you have more nobles you're more likely to win, period. This is less of an effect when the # of nobles in realms are very high for everyone. But whwen the noble counts are low (as they have been getting lower recently) then the difference is much higher.
If the realms are 60 nobles and 80 nobles, then it doesn't make as big of a difference if the realms are 30 and 40 nobles, or 20 and 30 nobles.
For a realm like the one I play in on Atamara, we are only limited in our military capacity by the # of nobles we have. We have enough gold and funding to make sure every noble in the realm has their maximum possible unit size. Thus, it is better for us to have more elite troops because we can afford the loss.
Unfortunately this is exactly how things will continue to be long term without massive more players in the game.
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Back on Topic:
I was under the impression that your likilihood of getting a good recruitment center was reduced the more recruitment centers that you had. (More troops already working elsewhere, etc...)