What are the pros and cons on the draft?

The pro-draft argument would simply be that the pool of potential soldiers is greatly expanded. The anti-draft argument would be that these people are conscripted and so are not particularly motivated to be effective soldiers. it is assumed that those who volunteer for service do so knowing the risks, obligations, and rewards involved. This does not mean that volunteers necessarily make better soldiers, just as it does not mean that someone who is drafted would not make an excellent soldier. In fact, one could easily argue that traits and talents possessed by individuals who are not inclined to volunteer might be extremely useful in a soldier. Independent thought, for example, might be a trait that would dissuade one from volunteering for duty as a soldier, but that sort of thinking creates great leaders as well. Conversely, patriotic fervor that motivates an individual to volunteer can be a dangerous trait on the field of battle, since overzealousness can get your own teammates killed.

In either case, it is of utmost importance that the wheat is separated from the chaff. This is what Drill Instructors are for, and they're very good at it. Their purpose is to strip people down to their beams, rods, and bolts, check for rust, reject the bad ones, keep the good ones, then build soldiers. On a statistical basis, this process would favor a draft. On a practical basis, it's not as clear cut.