Lion El Johnson. First son, First Legion, tactical genius and survived for 10 years on a death world as a wild man before being found. Russ ain't got shit on Johnson.
Sanguinius, Horus said that he should have been made Warmaster due to his martial and diplomatic skill... All the other primarchs listed has some sort of flaw. Lion El Johnson is a coward who couldn't choose what side to be on. Leman Russ is meant to be restrained by a leash. Roboute Guilliman is Roboute Guilliman.
"I am not like my brothers.....or Russ who howls and all the wolves in the world howl back at him..." - Urizen the Auralian "Lorgar" - First Heretic Just epic covered in spectacular dipped in werewolves the Wolf of Fenris is by far the greatest amongst the 4 starters and argueably the greatest of all the Loyalist Primarchs heck Prospero Burns features atleast 3 non-Fenrisian characters stating the Space Wolves to be the strongest Legion with one being the Primordial Annihilator himself who explains how he and (I don't recall if it's implicitly or explicitly) Horus orchestrate the sacking of prospero to take the space wolves the "Strongest Legion" and single largest threat to the Heresy off the table...but hey who can argue with a bunch of guys whose strategy is "Attack the enemies single most powerful point first with your entire army" and then proceed to drop assault even jumping out of thunderhawks/drop pods to hit them faster. Plus the Wolf is the only Primarch save the Lord of the Red Sands who is Orky enuff to give a gud fight!!