3. Angron (beated Leman Russ and Guilliman)
Y'mean that time Russ let Angron beat him as to teach him that winning the war is more important than winning the battle?
4. Fulgrim (perfect duellist, defeated an Avatar of Khaine)
Bending over an Avatar of Khaine and fucking it's candy ass like you're in a prison washroom is one of the basic entry requirements to get into the fluff, everyone does it. However, since Fulgrim has the highest Primarch kill count, even if one of them is by a poisoned sword after he turned into a giant daemon snake centaur thing, I won't say you're wrong.
5. Leman Russ (defeated by Angron, beated Magnus)
Yeah, but he was covered
in anti-psyker fetishes and accompanied by the Sisters of Silence when he fought Magnus, and he lost to Angron on purpose.
6. Vulkan (beat Curze twice)
He beat Curze once that I know of, but Curze fought and killed him about a dozen times on Macragge and was only stopped by Matt Damon throwing a daemon at him.
The average ones
7. Roboute Guilliman (defeated by Angron)
But beat 'enlightened' Lorgar like the red headed stepchild of a rented mule.
10. Lion El'Jonson (defeated Curze)
Beats Curze in a fair fight, but when Curze fights how Curze fights, then he's only saved by Corswain stabbing Curze through the spine
and even then, it's a draw. Then tries to double-team Curze with Roboute, and gets absolutely wrecked, only being saved by an arcane teleporter powered by pure, unadulterated bullshit.
12. Ferrus Manus (killed by Fulgrim)
Chatted shit, did nothing of note, got wrecked.
The weak ones
Konrad Curze (beaten by Vulkan and Lion El'Jonson, overcoming Corax)
Beats a weak Corax, so we won't count it, but beats Guilliman and the Lion at the same time
, draws with Sanguinius (remember that Sanguinius projects a psychic aura that forces everyone in the vicinity to fall to their knees and suck his angelic dick over his amazing amazingness - even other Primarchs), beats Vulkan like the ass of a mule rented by a red-headed step child. Loses to the Lion one time. Also manages to stay awesome despite the best efforts of Black Library.
15. Rogal Dorn (beaten by Curze)
No, no, I think you've made the mistake of thinking that Dorn's done anything ever. He doesn't lose
a fight, he doesn't even have
a fight. Curze jumps him for the crime of being a two-dimensional prick and near enough kills him with his nails and teeth.
16. Magnus the Red (beaten by Leman Russ)
Implying that Russ ever accepts a fight he's not guaranteed to win?
17. Alpharius (physically shorter than his brothers, likely beaten by Guilliman)
Nah, wait until the 30k series covers Eskrandor. There's not a snowball's chance in hell that Black Library will ever let the Alpha Legion ever lose anything ever. Also I assume he's the same size as a regular Primarch, he's just got a super power that lets him pretend to be an ordinary dude (Corax has invisibility and Mortarion can teleport, nothing would surprise me at this point)
If Black Library had a shred
of consistency then it'd be an interesting discussion, but given that the Primarch's fighting abilities (hell, all of their abilities) can be summed up as 'whatever the current plot demands them to be', any Primarch could fight any other Primarch in a BL novel and we'd have absolutely no idea what the outcome would be (Lion and Guilliman fight Curze, and lose
, but are saved by the power of friendship).