There's only one correct answer: it depends on the complexity of the object you're modeling and the level of detail that you need.

Poser is a bit special because its smoothing isn't as powerful as what other renderers have, and also because people like to morph the heck out of the models. I'm reasonably sure V4's original mesh had around 15k polygons, but it was subdivided once to satisfy the polygon hunger of Poser users. Antonia originally has less than 10k. An experienced modeler working with professional software would probably find that excessive.

-- I'm not mad at you, just Westphalian.