If you are wanting to create animated 3D models to get sprites from, I'd recommend Blender. It's free, it has a crap-ton of features, and it supports high-poly modeling and animating. And on top of it all, it even has its own renderer. (although you do have the option of using a ray-trace renderer like Yafray) There are no restrictions on rendering (like there are in some trial versions of software packages) so you can go hog-wild. It will export to almost any image format, and it supports exporting alpha channels. (great for rendering sprites)
Deriving sprites from 3D models is not the best way to go about it, but it is certainly one of the fastest. Animating 3D models is much, much faster than animating 2D sprites.