So, we know that (in most continuities) there was a time before the Autobot/Decepticon divide, when Cybertron was ruled by a variety of different factions/nation-states, each of which was presumably represented in the Senate (and/or the Council of Ancients). Then the war started, and the newly-appearing Decepticons started vacuuming up several of these factions, forcing the Autobots to do the same, until only the two sides were left.
For the sake of worldbuilding, I've been trying to suss out what these pre-War factions on Cybertron would have been. I'm looking at them as distinct cultural groups, each with their own cultural identity and "genetic" heritage --Transformer reproduction probably doesn't select for traits the way biological reproduction does, but I'd guess that faction-specific programming/body-types would create a similar effect (you could even have halfbreeds, with newly-designed body types and mismatched programming code derived from two or more "parents").
I'm operating under three assumptions here, as starting points:
(A) That each faction would have been created (either by Primus or the Quintessons, whichever) to serve a particular purpose. This would influence both their physical forms and their hardwired programming, resulting in (what might as well be) "genetic" predispositions.
(B) That each faction had its own home territory, and would thus have some degree of cultural isolation. This would mean that there would be pressure toward societal conformity --the "nurture" side of the Nature/Nurture principle. There would also inevitably be "fringes," where the non-conformists would end up rubbing shoulders with foreign cultures --and thus adapting to unexpected social niches.
© That each of the original "Primes" represented one of these factions, for thirteen original factions in all (plus any emergent hybrid populations where two or more factions end up sharing a border and swapping code). Of course, we still don't know all of the Thirteen, so matching archetypes to factions is difficult.
Here's what I have so far:
SEEKERS: Designed for flight, whether combat or exploration. Culturally, they tend to be prideful and brash; before Megatron (or rather, before Starscream), it was unusual for a Seeker to willingly submit himself to a non-flier (this is, in fact, the whole reason Megatron had Starscream installed as the leader of the Seekers --if the others saw Starscream obeying him, they would fall into line with the Decepticon cause). While we all know Starscream and his squad, I also count Powerglide and the Aerialbots (and Skyfire, of course) as renegade Seekers who joined the Autobots.
CONSTRUCTICONS: Designed for construction work and engineering, these are the descendents of Solus Prime. Constructicons are natural collaborators, with a cultural predisposition for teamwork and group cohesion (which is why a group pf Constructicons was chosen to pioneer the Gestalt process). At their best, they are also creative, pragmatic, and gregarious. While many sided with Megatron, Hoist, Grappel, Erector and others jumped ship and joined the Autobots. Boulder is a Constructicon, accounting for his artistic interests (Bulkhead also has some Constructicon code in him, as demonstrated by his artwork).
DESTRONS: Intended for advance combat, the Destrons are as strong as the Constructicons, but more aggressive --and ambitious. In peacetime, the Destrons were the ones who bristled the most under the Council's rule, and many of them were forced into menial jobs, or consigned to the gladiatorial arenas. The then-nameless Megatron was once a Destron energon miner, and Shockwave would have been a tactical strategist if he hadn't been forced into science (and discovered a "talent" for it). Roadbuster, Whirl, and Warpath are Destrons who ended up with the Autobots.
PROTECTOBOTS: Created for civil defense (including law enforcement, fire suppression, medicine, search & rescue, and emergency repair), the Protectobots are probably connected to Nexus Prime (whose function was tied to guardianship). This group includes not just Hot Shot's squadron, but the ancestors of Prowl, Fixit, Siren, Barricade, Smoulder and others. Protectobots love Order above all (and many of them are devout Primus-worshippers), making them conservative and disciplined, though this can also make them rigid, rule-obsessed, and ill-suited to change (this is why Prowl is a dick). Of course, many young Protectobots actively rebel against this cultural inertia, which explains the likes of party-loving Ratchet and epicurean Sideburn.
COMMUNICATORS: Intended to be broadcast engineers and data managers, they are descendents of Logos Prime. Mechs like Blaster, Eject, Rumble, and Flipsides tend to be gregarious and chatty, as eager to distribute information as they are to collect it (Soundwave being a notable exception to the rule). Cosmos and Hubcap also come from Communicator stock, as per their original functions.
MICROCHANGERS: The thankless bureaucrats, administrators, and aides, these were intended to be domestic servants and office assistants. They tend to value intelligence and cunning more than strength, and are often (though not always) small and weak. Cerebros was a uniquely brilliant Microchanger scientist. Senator Ratbat was the Microchanger representative in the Senate, and he was the one who introduced his kinsman Swindle to the young gladiator Megatronus.
MALIGNUS: Designed as military hardware intended for infiltration and stealth, the descendents of Amalgamous Prime were (allegedly) the ones who invented transforming (whenever any other faction claims credit, the Malignus explain that the inventor was only pretending to be part of the other faction). While Sideways is an iconic figure, Jazz is a rare example of an Autobot-aligned Malignus (which explains why he took so quickly to human society --cultural assimilation is in his programming).
PRIMITIVES: Primitives were intended as explorers and wilderness scouts, and can go for long periods without refuelling. The idea was that the Primitive could be dropped on an uninhabited planet and left to wander around, then retrieved and debriefed. Because of this intended use, Primitives tend to be self-reliant and independent, and they do not play well with others. Many of them are non-sapient "animals" (turbofoxes, glitch-mice, and pneuma-lions are among them), and even the more advanced units will tend to adopt beast-like alt-modes whenever possible. Grimlock is the standard example, whose main reason for not joining the Decepticons is because everyone else was.
INSECTICONS: Like the Primitives, the Insecticons were intended as interplanetary colonization tools; miners/terraformers could drop a supply of Insecticons onto an uninhabited world, and these self-replicating machines would begin consuming everything in sight and using the resources to create more of themselves (leaving rare isotopes and precious stones behind to be collected). They were unique in that they were the only mecha to be able to reproduce without access to Vector Sigma or the Matrix. During the war, Shockwave performed experiments on Insecticons, seeking to duplicate the Insecticon reproductive process (a necessity since the Autobots controlled the Matrix). These experiments gave rise to the Insecticon Swarm --a subspecies of Insecticons who reproduce so quickly that most hatchlings end up malformed monstrosities. Airachnid, Wasp, Bugly, and Blackarachnia are descended from "purer" Insecticon stock (as are Shrapnel, Bombshell, and Kickback, of course).
DIACLONES: By far the largest faction, Diaclones are general utility mecha, and were often "adopted" into other clans. They could also be related to Nexus Prime, reflecting his multifaceted and changeable nature. Designed to be useful just about anywhere, Diaclones can be anything from recreational goods to high-speed couriers to family transports. When people talk about the Autobots being "consumer goods," they're thinking about the Diaclones.
CONVOYS: Designed for long-range cargo hauling, Convoys are the providers and supply coordinators of Cybertron. Often coupled with external "trailers" that can serve as anything from cargo pods to repair bays to mobile energon refineries, Convoys are large and powerful enough to deliver both speed and towing capacity, and smart enough to determine the best route between multiple destinations. It is this planning ability that made Orion Pax such a skilled archivist (he could treat the archives as a mental map, and draw connections between different points that no one else would notice). Hauler, Pipes, Roughstuff, and Toxitron are also Convoys.
THETACONS: Defensive specialists, intended to supplement the advance troops. Thetacons tend to be large, tough, and doggedly loyal (if not always very bright). When a Thetacon gives his word, he will die before breaking it. Despite their military natures, most Thetacons sided with the Autobots --Cybertron's rightful rulers. Ironhide's Thetacon roots are apparent in his loyalty to Optimus Prime, as are Lugnut's in his loyalty to Megatron.
DECEPTICONS: Originally created to be Cybertron's defensive corps (and to serve as oversight over the closely-related Destrons and Thetacons), the Decepticons were as intelligent as the Microchangers, as cunning as the Malignus, as aggressive as the Destrons, and as powerful as the Thetacons. After the Quintessons were expelled from Cybertron, the Decepticons became the planet's army and secret police. When their leader Megatronus Prime was exiled, many followed him, while others were assimilated into the other factions. The name of "Decepticon" was stricken from the records, and the entire faction was erased. Eventually Clench, one of these old relics, ended up in the gladiatorial pits, where he met a young nameless Destron. The Destron heard Clench's stories, and decided to resurrect the Decepticon movement, taking the name Megatronus. . .
AUTOBOTS: Long after the dissolution of the original Decepticons, the High Council created a new 13th faction. Unlike the Decepticons, the Autobots would be formed only from volunteers. It was hoped that this would make them immune to the political infighting and manipulations that were wracking Cybertron (now that the Decepticons were no longer around to maintain order). The Council of Ancients bestowed the Matrix on Primon, naming him Alpha Prime and making him the first "Prime" to not be an original prototype.