Infinite has the ecosystems.   They are very clever, if also a bit infuriating.   I think that the render quality for Esprit is supposed to be slightly superior to that for Infinite, but the ability to generate ecosystems generally makes Infinite the preferable option (also, though, the much more expensive one).   Vue is capable of importing a pretty well exact copy of a Poser file (poses, materials, the lot), but it hoovers up masses of memory in the process and the results are not bug-free.   Vue seems to function perfectly in a 64-bit OS, with huge amounts of memory and multiple CPUs.   I like Vue a lot, but, running it 32-bit, with a single CPU and 2Gb of memory (as I do) does reveal a fair number of problems in the interface with Poser.