If you are looking to do a DIY hunt, check out how much public land is available. I think NE WY has pretty limited public land and access to this land is not great. I think I read this in an Eastman's MRS evaluation of this area a few years back, but you should verify.
Not familiar with NE WY hunting, but have hunted SE MT a bunch. We usually look for a MT BMA that takes reservations or a trespass fee hunt. Most public there is pounded pretty hard, but a public hunt is doable. Populations have been good since the last die off, smaller bucks all over the last couple seasons where we were, some better ones too. This winter has started out pretty hard there, so watch that and consider it in your plans.
WY has walk in areas, they are worth checking out I suspect. MT deer tags are expensive, 600+, which stings. There are plenty of opportunities all over in either state, not just those two corners.
Region C within NE Wyoming is pretty tough access-wise. You are right, decent quantity, average to slightly below average on quality - just not much opportunity for older age classes to develop on the limited public ground. If you could score some decent private access (even as easement through private to access locked up public), NE Wyoming would be worth considering, but I'd lean towards Montana if I were you.