>>307258152
With shape keys, you have less skinned meshes, but the clothes/verts still gets rendered.

With seperate meshes, you have more meshes but disable the meshes, so they don't get rendered at all.

I would say having more meshes is better then shapekeys in this scenario.

In general, just be medium or better rank and it's all good. As long as you don't go out of your way to performance grief(fur shader etc)