The Argent Crusade has undead members and is the only group to have had success reclaiming any major part of Lordaeron outside of Tirisfal and Silverpine. One of their oldest and most respected members is an undead, with the title the Revered.
Scarlets are the only group that’s shown any inclination of actual… crusading in that fashion, and they’ve utterly failed every time to actually hold the land they take, none of said land taken having actually been in lands held by Forsaken (barring the monastery). You push them out in the leveling zone of Tirisfal and then they never appear beyond that in Cataclysm until you get to Eastern Plaguelands, where the Brotherhood of the Light promptly gives them a final beatdown.
Lordaeron does have some holy land parallels, it was the primary center of Light worship and the architecture is fairly Byzantine (domes and such) but the only people trying to reclaim the place, unlike the real world crusaders, are the ones who actually lived there or groups led by those who lived there.
All the groups trying to take Lordaeron/settle it have an equal claim, it’s just some (the Scarlets) are more insane than others and incompetent besides.