NY! Camilla

All of them are decent, at least. NY!Azura is surely the best of which, bringing very good support abilities.

Depends on your needs.

NYAzura is the first flying dancer, but fliers can get by without her, and you have access to a free dance in Olivia. Plus we have six other dancers on top of that. She is now the third one with Hone Fliers as well. There are some good builds for both fliers and mixed teams.

NYCamilla is outclassed offensively by Elincia. She does have decent defense, but Palla is a serviceable replacement that we already have. Plus Palla is easier to merge. NYCamilla does come with spd/def bond, continuing the bond skills, along with the rare ward fliers. Though you don't see many defensive fliers teams.

NYTakumi is a decent dagger user, though daggers are still kind of lost in the meta outside of niche roles of infantry and mage killers via Poison Dagger and Kitty Paddle respectively. He does come with a slayer/debuff dagger which is good, but not game breaking.

Overall this is kind of an underwhelming seasonal banner. Unless you are a fan of those characters, or you need some skills none of them are a must have. Having more dancers are always nice, but not a necessity.

It depends on what exactly you're needing. As far as being worth summoning for, the only character that I feel like isn't "worth" the trouble is Takumi.

Azura can fly, is a singer, and has Hone Fliers. Those three things make her worth summoning for. There are only 3 units with Hone Fliers, and one of them can't be obtained right now (Halloween Nowi) so it's nice for people trying to build Flier Emblem and don't have a Hinoka.

Camilla is cool, I guess? I don't have any flying sword users except Palla (I only use her because Goad Fliers) and Caeda (Her attack is uber low). Although, looking at stats, Palla could be a good discount. Her attack isn't that bad provided you have an +attack, same with her speed. Her Defense is also pretty good, same with her Res stat. It's just that her sword, Ruby Sword, would probably be switched out for something else, and she doesn't have a bond skill like Camilla.

NY!Camilla has a BST of 162, which can be useful if you are trying to climb the Arena with a Flier Emblem team, because it is the highest BST a flier have actually (Only 2 points lower than Fjorm). Outside of that, she is a good red unit that would certainly make great use of the Iote's Shield seal released with the current TT.

NY!Azura is a flying singer, with a crazy good offensive stat spread (Only 1 point lower than Cordelia in atk), which can let her run stupid builds like Brave Axe builds or Desperation Heavy blade Galeforce to deal with a annoyance before dancing another unit for mass destruction. You can also run the classic WoM singer, she will do it better than the others because she fly, and therefore can pick you up between a lake and a mountain. But she is a singer, and singers/dancers have a low BST. Flexibility is the counterpart.

NY!Takumi has the best dagger in the whole game (exit Deathly Dagger), and if you like a certain dagger user, he is worth.
He also has a nice offensive stat spread that allows him to deal substantial damage to a lot of people, but his defense stat is terribad, tho. Waste of Bowbreaker.