Depends upon what you want in a cartoon render. Poser offers several options, including:

The cartoon display modes ... these use the preview engine, which can generate dozens of frames per minute. The P6 preview engine uses OpenGL hardware acceleration, and looks much nicer than in earlier versions. You have more control over the toned shading, highlights, and line-thickness.

The Material Room's toon shader node ... which works with the Firefly render engine. Slower than the preview engine, but allows you to use transparency, textures, and shadows. The inked lines aren't generally as good.

Poser 6's new toon outline option for the Firefly renderer ... a postwork filter which adds outlines to the render. Has several style options (thick pen, thin pencil, etc.). Unfortunately, it outlines everything, including the edges of transmapped materials, and the outlines tend to have aliased edges.