If there's one constant among Transformers fiction, it's the ability to create interesting and dynamic universes ... and then do nothing with them.
Thankfully, that doesn't always hold true, and we've gotten a number of fun and engaging stories over the years.
But it's always there. That comic or cartoon you begin with such interest, only to watch it fall into a hell of its own making some issues/episodes end.
So, what are the series that, in your mind, have the most potential and the most disappointing outcome? Note that this isn't necessarily your least favorite series; it has to have some merit that it fails to live up to. For example, I think Armada is terrible from its first minute onward, so it wouldn't be a candidate for this thread.
1. Energon - A series so universally reviled its TFWiki entry has en entire section dedicated to mocking it. I truly think this is the most squandered Transformers series ever made. It's not the best; it may in fact be one of the worst, but that's particularly tragic because, in concept, it does a number of things I enjoy.
It introduces a number of elements never before or not often seen in Transformers. The relationship between the Transformers and humans is incredibly interesting, with humans allowing them to set up bases on Earth but electing that the conflict isn't something Earth nations should step into. The dynamic of what to do with Unicron is something that's never been done elsewhere. It gives us a human protagonist who hates that his family has shoved him into constant interaction with the Transformers. It gives us Transformers who reflect on human mortality (!). It actually brings back the large-army format of Generation 1 pretty successfully, which is a refreshing concept now. Its version of Megatron is genuinely scary, and by all rights, it should have the most interesting interpretation of Scorponok outside Marvel G1.
That's all in concept. In execution, we all know what we got. At least the soundtrack is still phenomenal.
2. The Michael Bay films - I feel dirty just admitting that. But honestly, there's a lot to like here. The designs are great. I like the background of the otherworldly "Cube" as opposed to the usual Primus/Unicron business. I like the idea of a dead Cybertron and an outcast Transformer race. I like their interactions with Earth governments. The Decepticons are genuinely frightening, and have no compunctions about killing large numbers of Earthlings. I like that the fight between Autobots and Decepticons seems to be more about pragmatism than anything else. I like kill-crazed Optimus, a lot. I also quite like the role of the human protagonist here to: their first human friend who's realistically bummed about being set aside for their more official jobs.
Unfortunately, everything else.
3. The Headmasters - Isn't this series often described as "sounding really awesome on paper, but being incredibly boring in execution?"
Because that's entirely accurate. The sexist portrayal of Arcee is just there to crank things up to eleven.
4. Transformers Prime - Okay, it's not really fair listing this here. It's just that it came from what is probably the best opening mini-series among any version of Transformers, a great introductory first season, good use of human characters and great B-plots to ... what we have now. But it's entirely possible that when all's said and done, the latter portion of season two will just be a blemish on an otherwise enjoyable series. Maybe.