In my opinion, Beast Wars was the best. The original series had a good rivalry between Optimus Prime and Megatron with good dialogue for both. But my issue with the original has always been that the Autobots and Decepticons, save the leaders, are write-offs; characters could come and go with little impact on the story. With Beast Wars, just about every character was well-written. Having a cast that only slowly grew in numbers meant that I came to like more than just the leaders. Add to this that the animation is still nothing to scoff at, and you have a remarkable cartoon that's worth a watch for all ages. I'll admit, they ended things on a sour note with Beast Machines. But that's because everything was formulaic and jammed into place rather than being the organic story Beast Wars was. If you seperate the two, Beast Wars is still a great series whereas Beast Machines is best described as "the failed experiment." People have this massive nostalgia for Transformers and everything that made that work, but if you look past all of the fond memories of watching the original on TV it should be obvious which one holds up as the years pass us by.