I am biased towards Rita because I love her so much that she was one of my first Awakened units. To be fair her skill makes her very useful in certain situations, and she gets more of an Awakening bonus than Bashira... now that I know I can acquire her later in this event, I'm going to see if I can get a few copies...
At the same time, while I got all drops on Forbidden Power of the Giants, I'm not sure what the platinum unit for it is... looks kinda like Momiji, who is another favorite unit of mine... sadly I haven't gotten a plat drop once, yet I've gotten five of Emilia from map 2...