If you go by the Horus Heresy 30k rules. Horus wins most of the time (number crunched by 4chan) If we go by lore well this is where it gets difficult. Most records usually point at Horus being the best. Not surprising as he was named Warmaster. Corax believed that no one could match Angron in single combat save for Horus and perhaps Sanguinius. This isn't hard to believe as he is the Primarch of the World Eaters and Leman Russ of Space Wolves was considered his equal. It's difficult to tell but the favorites would be Horus, Sanguinius, Magnus and Dorn. Sanguinius has been called the 'closest' to the Emperor and has broken a Bloodthister's back on his knee. Rogal Dorn and his legion held Terra against literally almost everything Horus could throw at it. He then participated alongside Sanguinius and the Emperor taking the fight too Horus himself (though by the time he got through, Sanguinius was dead and the Emperor was practically near death himself) Magnus, because he was THE psyker matched only by Malcador the Sigillite and only surpassed by the Emperor.
Apparently Leman Russ is the strongest of the released Primarchs in the 30k TT. Its funny because in the fluff Angron beats Russ, but in the TT Angron can't beat half of his brothers in the first place, nevermind Russ who can beat fucking Horus. https://1d4chan.org/wiki/Leman_Russ
In straight up melee combat Russ or Angron. All else Either Magnus or Mortarion. Can't fuck with the deluge of chemical/biological rot or the endless fucked up stuff of the Warp. Even Primarchs can get fucked up by either or both eventually. Magnus' Psyker power is nearly omnipotent and Mortarion doesn't have to land a single blow, he just needs to last long enough for the rot to do its thing to his opponents. I love the Wolves but ****SPOILER ALERT**** if Magnus hadn't been moping around when the Wolves were wrecking Prospero im not so sure the outcome would be the same. I don't think the Thousand Sons of the Great Crusade could ever have been matched or defeated with Magnus head out of his ass and in full battle form at that point and time.
In the fluff the battle between angron and leman. Leman let angron win to prove a point, that angron works as an individual whilst leman works with his wolves as a pack. I think the incident was called night of the wolf. Just don't forget the good good old kharn. Went toe to toe with Mortarian after fighting psyneuin.
+1 SPOILER ALERT..... Kharn ***The Red Path*** Correct me if I'm mistaken, wasn't Kharn kicking Abaddon's ass in the last or next to last THE RED PATH novellas? Didn't Kharn basically choose NOT to kill him? I can't recall exactly. I need to reread the end of that series. But that's Kharn now, vs Primarchs back then.
Not read that yet. Probibly will read it all next month. But really good old kharn for killing everyone again
I was under the impression that in that book Russ was actually beaten, but was prepared for the possibility of losing the fight and got some of his marines to help him out if he did lose. Also Kharn when toe to toe with Mortarian....... god damn. what book is that from btw?