Cybertron, man. What a time. What a toyline. What an absolute peak of this franchise's history.
At this point Armada and especially Energon had kind of disconnected me from the fiction and had me living 95% in the toys. Then, Cybertron was first felt in reveals of something called "Galaxy Force". Designs, show models, then toys, and the buzz was about. I wasn't really invested in whether or not it continued on from Energon -- I don't think I knew or cared at the time how the Energon series had even ENDED, despite riding very high on the toys. But the
initial reveals of Convoy, Megatron, Dreadrock, Exillion, Vector Prime, Guardshell... these designs looked amazing, especially as a further design evolution from the Armada and Energon lines. Nicely-proportioned, neat design elements, all looking fresh and interesting while still feeling very Transformers-y, NONE hampered by a top-down powerlinking gimmick -- all making for an exciting time. Starscream was the closest we'd gotten to a version of the old tetrajet, Dreadrock seemed like a simple transformation that turned out to be a nice and hefty-looking robot, and Vector Prime was a gorgeous, ancient, ornate design (if one with a weird altmode). And, of course, Convoy/Optimus Prime was a sheer
triumph, going from a very substantial altmode to an incredible stylized bruiser of a robot that had "this is THE leader" radiating from its every surface.
This was a great few years in general, coinciding with a part of my life I still look back on fondly (in that it was complicated enough by grownup obligations to be interesting and not TOO rose-tinted, but still far away enough from the complexity and occasional despair of now to fittingly be called Simpler Times). And Cybertron was the crest of it, leading into another renaissance in the Movie era (that was accompanied early on by continuing uses of Cybertron molds).
To this day I'm not too familiar with how the show went and ran, but I gather it was much better received than the previous ones, and did a good, fun job with its dub and the new characters/concepts it introduced and played with. Maybe one day I'll rediscover the show, but I'm more than sold on the strength of this diverse toyline alone.
The simple brilliance of a narrative excuse to throw in a bit of everything (itself a great way to open the franchise lore at the time WAY up) resulted in a line that had, well, a bit of everything. And in an intentional way that all hung together cohesively, unlike how homage lines like Legacy are also "a little of everything" in the way that a supermarket is also "a little of everything". Beasts, Earth style vehicles including a Dauphin rescue copter, a muscle car, and basically a Bugatti, greebly futuristic Cybertronian vehicles, Mini-Cons, gigantic vehicles, weird angular otherworldly spacecraft, new decos and looks, a robust amount of homage-themed ones, and even a line-wide gimmick that managed to not compromise the toys too much (and other gimmicks like being Prime's armor bits that also still kept the main toys good-to-great).
AND Takara was cooking up some additional fun too, with Armada mold retools into Longrack, Blurr, Runabout (Cyb Runamuck), and Buzz Saw. AND they'd get their Mini-Cons in a Micron Booster set, AND some neat exclusives. AND Hasbro kept it going with the Primus Unleashed subline imprint, which added the first ever mainline Primus (and capped off the trilogy with another planetformer), Mini-Con versus packs that had some neat lore of their own, and homages like Excellion (which, man, I don't think I've anticipated a toy of that sort more -- even Studio Series 86 Hot Rod himself didn't hit like this did for me).
The toyline had undeniable misses. Some otherwise-nice toys were
still designed in a way that resulted in them lacking basic joints (Scattorshot, Scourge), and some others had different flaws -- Override's transformation gimmick, Thundercracker's floppy too-long arm, and the fiddliness of getting Soundwave into his altmode are strikes against still-fun toys. But these were blips in a tide of great stuff, with some new designs being among the best achievements of their era. Even the PACKAGING I would put up against anything from any TF series (there was a run there in the 2000s when Hasbro's packaging game for most of their lines was on a hell of a roll). This was a line with so much... texture? and I never wanted it to end.
This I think was the most fun a kid-oriented main line has ever been, and the most attached I've been to one. The only other time I've had as much affection for a line is with Botbots, and that's not the same kind of line at all. I'd contend that none of the also-quite-good kid/main lines since have really matched it (despite some having such potential to), mainly because the role that such lines play for the brand has changed so much. They all do their thing well, but it's not the sort of thing a line needed to do during the UT (before the Movies changed the brand's scope going forward). Not any Movie line, not Animated, not Prime, not RID2015, not Cyberverse, not EarthSpark. None of them is as everything as Cybertron, and it's a good thing none of them need to be.