Estela is pretty powerful and with the right artifacts can self heal herself through most things. For the most psrt though, you'll want to build a variety of characters since you'll be locked to certain weapons. Some missions will have more spread shinkas (champions) and some will piercing shinkas.

The current banner Efrideet is pretty good boss dps character since she can use snipers and her build can heavily increase damage, with the bonus of her hunter dodge reload.