I don't know nearly enough about the canon capabilities of the warrior priests of Sigmar to give input here. I would say that in terms of wc3 lore you can certainly have more than one paladin in a large army. Wc3 game mechanics mislead in that regard. Ironically iirc even in wc3 lore, only truly powerful paladins were capable, or considered worthy of being taught raising the dead, so in terms of average paladins that may not even be on the table in skirmish or large battles. I do believe the aura of devotion likely translates better canonically in scaling for large armies... also, in terms of canon I am pretty sure wc3 paladins could heal themselves. That was mostly a game mechanic limitation for balance's sake. However I do think the War Priest's abilities are probably better in such a context. In general, I think I agree with most of the conclusions drawn here. Even with the ability to heal himself a paladin in wc3 wouldn't be as zealously viscious to attack a Sigmarite war priest as the Sigmarite would be to attack the paladin, and soulfire is an offensive ability, which wc3 paladins did not have for use against humans that are not hurting innocent people... although this changes if the Sigmarite does attack someone the Paladin thinks is innocent. Wc3 lore does state paladins can weild holy fire against all those who would trample the meek and innocent. This becomes an entirely different fight in WoW. Fanatical, zealous, wrathful paladins are common in WoW and would likely smite the shit out of a Sigmarite warrior priest... there can be many paladins in armies giving a dizzying array of buffs... However there is an interesting caveat here... the Holy Light is indiscriminate in WoW. The Sigmarites faith may in fact give him access to the power of the Holy Light without him even intending to access it.
I'm putting my money on the Paladin here. Even without Divine Shield, the Devotion Aura would already make his tanky stature even more unassailable. Not to mention how buff the Paladin is compared to the Warrior Priest.
Well, the Warrior Priest doesn't believe in a wibbly-wobbly subjective force that will support anyone who simply believes in their own cause strongly enough, regardless of whether or not they're right. So...
Which is funny when the canon explicitly states it requires one to be "human" (as in adopt human culture and values like high elves that joined up during the first 2 wars did) to use it and any other use of power is arcane sleight of hand or demonic corruption, much like the winds of magic ask for the proper rites to be safe. I do love it when old writers pre set clauses that make future retcon attempts shit themselves (like age of sigmar did to itself).