Cool game! I mostly ignored the story, but I can give my toughts on the mechanics.
I went for the Dragon start. I tried the Harpy for a bit afterwards, but the extra 64 mana per day is simply much stronger when you know how to set it up. It looks like it can be abused a bit: if you have a Rest link available before you Convert you can send to Ollie more than your maximum mana. The Dragon's self impregnation also gives both 1 regular mana and 1 Draconic Mana, making it the most efficient way to raise your mana.
The other way to maximize your mana gain is to assign almost everyone to Emily and Festival everyday to take advantage of the discount asap. This is annoying because every assignement takes you to her, you have to navigate back to the city. This is only going to increase as the number of characters increases.
I prefer how Festivals worked in Albero Verde, needing a certain number of candidates. You could ignore certain characters without having to interact with them (to assign them to Emily). You didn't have to meet with everyone before your first Festival. You couldn't start doing Festivals everyday right from the start.
In any case, I look forward to see how Amber Burrows develops!