ZRemesher does as good of a job as any other package’s decimation. In fact, unlike most decimation algorithms, ZRemesher is going to give you nicely deformable animation. Sometimes you need to give it some hints with vertex colors and ZRemesher Guides, but it’s still pretty fast. I’d highly suggest dropping your poly count right in ZBrush, as general purpose 3D apps like Maya and Blender really don’t handle poly counts that high anywhere near as well.