I believe we need more data about some things before we can proceed:
First, what do we know about slimes? And Zayan and Barbatos about that matter as well. From what I understood, these seem to be widely considered above average punching bags, but they don't have to be necessarily mindless creatures. They must have some form of communicating with other species at least (even if it consists in "consensual tentacle prodding"). One thing for sure is that they most likely can inflict nasty side-effects with their attacks, which are doubly effective against female beings for obvious reasons. On the other hand, perhaps we can eschew the need of disguising ourselves, since slimes would simply recognize us as another inhuman sooner or later (I recommend we take a female companion if we end up visiting the slimes, that should make them eager for "dialogue"). However, I believe we must develop our illusion magic before going to Yuria (assuming we have time for an additional trip). Their slime leader may or may not ask us to attack Yuria as part of the deal of joining us though (which won't be too bad IMO).
Second, what about dryads? Besides being forest spirits, depending on how much they care about the surrounding world, it may be possible they won't wish to interact with an aspiring Overlord (unless they only care about their forests and little else, which is a possibility). Either way, disguises and illusion might not work against them, since fairies are already experts at trickery and deceit.
Third, about the Angel of Methuss, assuming it's here and we can release it, I expect he or she is used as a power source of sorts, only being allowed to leave for rare occasions (such as "search and destroy" missions which need extreme firepower). In the rare case we free it without nasty consequences, we would have the trouble of having a new
ork companion whose lust for battle makes Rin look like a pacifist, which will limit our future non-violent approaches somewhat. Worse, if it's male, he may take a liking towards our Fumblerina due her similar views about battle and violence. Worst case scenario, the angel will take her when we're away somewhere else.
Fourth, has the healing chamber been completed by now? Along with Erdrick's missing wing as well. If so, is he able to maintain flight? Might be useful for scouting if done well.
Lastly,
treave, would you kindly repost the stats for our goblins companions? Just for completion's sake and/or know which ones to take.
EDIT: Also, I updated my votes to:
1. B.
2: II + IV.
3: Lucy + Aria.