I think the labels got reversed in mf193's comment -- the RayTracer is the slower, but higher quality rendering engine. The hybrid renderer renders only the edges of objects, any transparencies and refractions and such; it guesses and just kind of fills in the blanks on the rest of the image (interpolation, I believe is the technical term for filling in the blanks). I usually don't use the hybrid except for tests early-on during the model construction process. After that, the hybrid just generates too many funky artifacts for my comfort level. For the best quality, stick with the RayTracer.