All of those are fine cleric heroes indeed. But between Mist, Lady Woolerton, Vivica, Hansel and Grazul, you emblem the hero you use more often in almost all facets of the game and enjoy doing so. I really can’t tell who would that hero be since we may vary in playing style and roster.
For Lady Woolerton, she’s a fast healer but her drawback is her inability to generate mana for two turns. However, this can be overcome by embleming her since the mana shield could potentially stop that negative effect. But of course there are other ways of countering that by putting in a team with heroes that can block that effect i.e Poseidon, Grazul, Gato.
If you’re looking for a hero that would pair well with most heroes, Mist is a good choice and she would be emblemed for her survivability so that she can fire her special.
c.Hawkmoon? No. Unless you have a ton of emblems. But she shouldn’t be in the list given that you have better priorities.
EDIT: also uclapack/dator made a youtube video on clerics. Perhaps that could help you make a decision.
Class talent and emblems were implemented in the live game sometime in the middle of January 2019. This was Version 18 and you can read the details HERE. Class quest was also beginning to appear and @Mariamne was able to formulate the ever useful Memento Heroes Classes and Class Trial Quests. Thus, mid-tier, advanced and veteran players were able to accumulate these emblems since they can finish all class quests stages while newbies and newish players could not since there was a level requirement and that the degree of difficulty in the last stage at the cost of 20 WE flags. The class quests, emblems sold at the Shop and with Magpie emblem offers, VIPs, chests, tourneys and even Mystic Vision contributed for the accumulation of these emblems.
If you began playing a year ago, then you were behind by 6 months and I bet you were not able to accomplish all stages of the class quest a year ago. This is main reason why some players have +20 heroes. The head start advantage by several months is now apparent.