G1

 

Transformers Animated, and I'll go in depth as to why. Not only was it well-written, it was fun. Prime is decently-written, but barely any fun to watch at all. Beast Wars was well-written and fun, but not to the extent of Animated. Also, the Animated designs were some of the best I've seen. Instead of most 'Bots having the exact same proportions and faces (most of G1) or being cluttered (the UT), they were sleek, streamlined, and most had vastly different proportions and appearances. They were also far more expressive than the Sunbow G1 models.

Finally, for the first time since G1's Spike and Sparkplug Witwicky, the humans weren't annoying. In fact, Captain Fanzone is one of my favorite characters on the show.

Basically, TFA is what I hold up as the best Transformers series, and would be absolutely perfect if CN hadn't cheaped out on the animation budget. I change my vote to Animated.

 

G1!!!