It depends on what your requirement for "best" is. Do you want to use Poser assets with minimal translation? Do you require physically accurate / non-biased renders? Do you need speed?

Personally, as an animator I'm looking for speed + quality. For my needs, there is nothing better than Photorealistic Renderman, as I'm sure several Hollywood studios would agree.

PRman's strengths include extremely fast render times in high polygon scenes (it was originally designed to render a 1500 x 900 pixel frame in one minute to be able to complete a 90 minute movie in one year) ; motion blur and displacements have negligible impact on render times; many intensive calculations (raytracing, AO) can be pre-processed and cached; it is completely extensible; the basic set of its controls are directly related to Firefly's and Poser has had RIB export since AFAIK version 3.

PRman's (apparent) weaknesses include lots of studying; nearly esoteric and exclusive user base; the command line version...is...well, command line; setup of raytracing is less intuitive than any other render I've personally seen; $$$$