Of the three legendary resurrect heroes, I don’t have Heimdall. His revive rate may be the lowest among the three, but he serves best as tank and over healer, not as a solid resurrect hero you can count on.
Meanwhile, Mother North is the hero with the highest rate of reviving fallen allies. She not only revives 50% of the time, she provides immediate heal and summons minions, which would have attack and HP stats increased if accompanied by other xmas heroes.
Lastly, among all the revives, I consider Alberich as the best. His revive rate is between that of MN and Heimdall. He is not as tanky as MoNo and Tootie, and he does not provide immediate heal but only heal overtime. What’s great about him is his mana generation over time, able to revive fallen allies and in just a few turns, those resurrected heroes have their mana fully charged and able to blast the enemy to thy kingdom come.
I would love to have all 3 of them maxed. Unfortunately, I don’t see myself lucky in the S3 portal. Back in 2018, I was wishing to have several more Albe, so just for me to have my attack teams in wars have a safety net having a resurrect hero (I was employing 4-1 back then).
In the end, all of those three need their emblems for them to be more sturdy than their base stats, giving you a high chance for them to survive better and get their skills casted, which may spell victory or defeat in the hit.
But the reckoning point is which of those choices do you feel like, if emblemed fully or highly, would serve best your raiding party? Those druids have each their uses. The forum users posting on this thread have already provided sufficient insight on which heroes to emblem. All is left now is to trust your gut feeling.
Good luck and happy gaming.