I like Star Trial events for reasons that have been already listed, guaranteed maxed unit, usually a good one too, challenging maps, and a lot of time to figure them out on your own without being rushed for optimization like in farm events.

Characters I like are Elves and white haired girls. But more specifically, I really like cool attack animations and abilities, so things like awakened Sybilla and Solano are examples of units that are unique and cool, whereas all the archers seem pretty same-y.

Characters I would like to see are Sapphire units if possible, Lolis if possible, and Western exclusive units would be cool too if possible.

I would also like to not skip any events if possible even though Star Trials are my favorite.

edit: Oh, and more story content etc. would be nice too.