Ghost ; If you like Dendro just go for her. She can fit well in any group as lead of ATK.
Don't worry about long term use, just choose the girl you really want.
I also choose girl I want when have chance Hoto-cnah and Seluria.

About event there is small window with main reward, I think we can use macaron to purchase that thing right away.
Will wait for stamina a bit and try it out if not forget.