*slams my hands down on the table*
now a lot of these do have smut and other mature themes so if those ain't your speed then DISREGARD
The Brave Shall Heed the Call by MlleMusketeer: SOOOO good don't mind the major character death tag it gets better. does have some potentially disturbing content so mind the tags. tfa, post-canon.
Peacemaker by Astolat: long one-shot, but it has Optimus defying orders for the greater good so :). tfa, also post-canon.
Ninth by Kyn: is a longfic with some potentially disturbing body horror, slavery, and megop is only one of the many facets of it but I HIGHLY RECOMMEND. It is one of my favorite fics OF ALL TIME. and considering how much I read fanfic that is a great honor. I also advise care on this one. Continuity soup of the most delicious kind.
Can't survive with you, can't survive without you by Tf_Tere: there was only one cave. tfa, I believe.
Ethics and Employee Management: A Love Story by pericitone: just about the funniest megop fic i've ever read. g1, I think???
Optimus Prime is Destined to Die!! by Chuzillla: SOOOO good!! It has mystery elements and, best of all, isekai. I would shout many more positive things about it if they weren't all spoilers. continuity soup, I believe, it's a royalty au.
Antiak Spaceport Cafe by Land_Locked_Martian: really funny, can't count how many times i've read it. tfa barista au.
Duobus by Cyndi: I really liked it, it's like this post-apoctalyptic thing where only the two of them survive. Armada.
Of Gutters and Galaxies by iliterallydecepticanteven: decepticon/autobot alliance my one true love. tfa. I'm only just now noticing how many of these are tfa.
Thus Spoke Quintus Prime by Anonymous: super funny, crack treated seriously. need I say more? Earthspark.
<Uninstall> by Zombieheroine: excellent enemies to lovers slowburn. incomplete, tfp
alright, that's all for now. I need to go to bed. let me know if you need recommendations for any other ships.