Beast Wars works well in appealing to children and engaging older audiences at the same time - whereas the G1 cartoon was primarily geared to appeal to children (and consequently was quite camp). Beast Machines is on the complete other end of the spectrum and only holds appeal for adults (I would be quite amazed if any child could properly appreciate/comprehend the themes in that show). Beast Wars was a good balance of being fun and action-packed enough for kids to enjoy whilst having a story that was written at a level high enough for older audiences to appreciate.

Both Beast Wars and Beast Machines tie into G1/G2 continuity and are loaded with G1/G2 references for the old school fans.

IMO Beast Wars is the best story ever written for a Transformers television series and the second best Transformers series written other than the G1/G2 comics.