i don't have a favorite; i mess around with the defaults stuff. ya'll remember the Tim0z mats? omg lol those were cool back then.
C4D's, easy, and difficult. 'Effect' renders are staggeringly easy to do, but, anything serious then it's going to be the same learning process as Photoshop, takes time. I usually make my own materials, particularly HDRI from photo's of, anything. Failing that, DeviantArt has the rest.