It really depends on the end use. If you are doing animations for broadcast quality television, or you are producing DVD for home viewing, or you are doing work for the web - all justify using a different codec. There are also issues with some codecs with rapid changes in scenery - some get it right - others leave artifacts of the previous frame. One issue for internet, or intranet use is the transfer rate required rather than the overall compression rates. I have tended to use the Cinepak codec for preliminary work and have recently started using the DivX codec.