It depends on what you want to do with them. Each is excellent. For some serious slime, check out Metaform. It's a python based metablob particle generator for Poser. One of the many things it does is allow you to specify any geometry as a generator, so you could create actual running, dripping slime with a little work (and a lot of patience; Metaform really adds to the rendertime, as the particle geometry is being parsed on the fly). Play around with some of Ajax's slime shaders (I think it was Ajax, at least.....), and you could animate the whole shebang. Or just pick one frame out of the animated sequence that looks right and render that.