>Which 12 star units are good?
That's a whole debate. Right now Evleda and Izane combine "pretty sturdy" and "relatively easy to get". Union, too.
The sub-units you got are pretty much on par with Union units (400 badges) but you can't use timed abilities and other shenanigans on them.
Astra, Zeinesis are very good too but limited to Deus and Mother EQs or trigger quests, and since we are not in a time of rare drop boost they're a bit more difficult to get.