I would be interested in seeing this go the other way, with various types of drafts that you can institute (as they do, after all, require a certain amount of sophistication that setting up a recruiting post for volunteers doesn't) including selective drafts, blanket conscription, and even slave warfare.

Selective Drafts would probably be more/most expensive, with high morale, and better soldiers on average (veteran soldiers are elite level, elite level are elite ++)

Meanwhile blanket draft would be less expensive, with lower morale soldiers.

Slave soldiers would be least morale, and on average weaker soldiers (veterans are like regulars, elites are like veterans, regulars are like greenhornes) ... Perhaps medium expenses yet MUCH faster to train, and also don't take from your population (or at least not your main population).

Volunteer army would probably have zero infrascruture expenses, however Each unit/soldier would cost more (+1 gold per unit as opposed to a Flat per-city maintanence fee of a civic) ... and morale would be increased, but perhaps not as high as the Selective Drafts. Actually, here morale and ability would be quite random, however morale would be greatly weighted towards positive, and ability would be slightly weighted towards positive.

Perhaps Egalitarian civs would have bonuses for using a Volunteer army ... like their volunteers would be more heavily weighted towards better ability and higher morale.

What I meant by selective drafting would be sort of a military state, spartan society. I considered Selective Drafting to be the kind where the people do their best to prove their worth ... and the government selectively picks the best candidates for their new units. Its kind of Spartan, its kind of Nazi.

Blanket Conscription is the kind where you pull a lottery of a bunch of hicks and hippies that don't want to fight. Selective Draft is not possible in Isolationist or Pacifist societies, so instead the Government submits a more random blanket conscription because NO ONE wants to fight ... or because the Volunteer army is already taxed.

You gave me a good idea though ... perhaps Selective Draft should only be in Evil alignment societies, or societies with a past of Warfare, while Volunteer Service might only be for good aligned nations or economically bound nations.

In the end, Volunteer soldiers would have their morale dependent on how "good" their Sovereign is acting, and Selective Draft would be, on average, stronger overall.

To be more clear, Selective Draft (or rather Draft by Merit) would be for people that "want" to be picked, in a society where the Government's rules are brutally enforced by the military. If you don't want to be picked, then don't show any athletic or leadership activities ... and youll either get left at the wayside or eventually brainwashed to follow along with everyone else.

Volunteer Service is for a society with a ruling middle class, or a common class of nobility, that Joins the Services for the protection of their privatised property and assets.

I suppose for some middle ground we could also have Vassalage(knights, samurai- a variation of volunteer service) and Caste System. A Caste System would be allowed to be used by anyone, and in some ways is quite similar to Vassalage. It would of course be a specific economic choice ... and give your units more "experience" while not really being stronger or braver. So maybe you get a couple extra levels because thats their lifestyle and livlihood and its always been that way, so thats all they know. So they will be better initially, but not have any particular Morale-based motivation or better Strength because you are not being selective, your letting an entire generation of people (an entire class) to join the army.

On the other hand ... perhaps having a Caste System could have other repercussions. People in the warrior Class might only fulfill Political or Military roles, so they don't help your economy any ... and you have less people to recruit from. In this case, they would need to be made much stronger ... but this is much more like Samurai than the Indian Caste system. (and we can't really judge their strength since they only fought peasants and themselves)