Can I just say again how dumb it is that the version of the Thirteen that's stuck doesn't even have thirteen real members?
The idea of "The Thirteenth Prime" being either Optimus Prime specifically or "whoever has the Matrix" is just...dumb.
The dumbest idea in an entire dumb book that was full of dumb ideas.
Dumber than fridging the first female Transformer.
Dumber than Megatronus not being really evil.
Dumber than the names "Megatronus" and "Amalgamous Prime".
I don't dislike the concept of the Thirteen... I think it's a perfectly fine way to flesh out the mythology. I just... have issues with the final list we got.
Alpha Trion- I love the guy but there was nothing special about him in the G1 show aside from being so old he remembered the Quintesson occupation. He was a mentor but he never seemed mythical. I suppose if you take his slave name literally he was one of the first sentient Cybertronians but ehhhh
Solus Prime- I like Solus Prime... in theory. She has a cool gimmick- blacksmith- and a cool motif- fire- and for a franchise that once said "NO GIRLS ALLOWED" to have a female character be the one who forged the Star Sabre and Matrix is pretty nifty.
What I don't like about her is 1) making her the "descendent" of all female Transformers and 2) having her get fridged for the sake of conflict.
The good thing is that this is fixable with future media. Don't make her the progenitor of all female Transformers, just make her one who happened to be a girl. Simple. I swear Transformers overthinks this stuff.
As for the fridging... I'd just rewrite the whole War of the Primes thing to get rid of that. There's no saving it.
Megatronus Prime- Good G-d I hate Megatronus Prime. The Fallen as a concept? Great. Love it. I'd just... kinda prefer it if we never knew his name. Like he was such a black mark on early Cybertronian history that they scrubbed EVERY reference to his name and he's just The Fallen.
If they must reveal his identity... Liege Maximo. Maximo is one I don't take issue with as a member of the Thirteen but he and Megatronus kind of share space as "the baddie" and muddle things. Like if the Thirteen shattered because Liege Maximo manipulated Megatronus why did Megatronus get the HE WHO SHALL NOT BE NAMED treatment but Liege Maximo didn't?
It just seems easier to have Liege Maximo be The Fallen and just have him play the general Satan/betrayer role.
Also the name "Megatronus" is dumb. It's like... bad fanfic levels of dumb.
Optimus/Arisen- No. Do better Hasbro.
The rest of them are fine honestly. Underdeveloped and not really characters (outside of Vector Prime who got to do stuff), sure, but fine. They don't bother me.
Alpha Trion doesn't really work for me, Solus is a neat idea executed poorly, everything about "Megatronus Prime" is dumb and embarrassing, and the decision to make Optimus a literal Messiah figure and reincarnation of a god is somehow worse.