hot 40K take; Lion El Jonson is an incredibly boring Primarch. Let's see, other primarchs include a literal angel, a hammer-swinging giant in dragon hide, Bulvyf from The Thirteenth Warrior, the Kha Khan, the only dude actually trying to make the Imperium be the good guys, and weird monsters.
@Leucrotta Fur real, tho. Better picks exist than the quiet blond dude.