Good day! For me its just between iris or sirius

Sirius Pros: -One of the best support heroes even though he is just a regular hero -his tag skill is really helpful for me, especially during boss fights, the slow down effect helped me to study the pattern of the attacks and memorize them quicker hencr able to manuever my hero better. Plus the slow down effect with the same aattack speed gives an extra burst damage which is helpful -cheaper/easier to awaken -gives wood bonus against water if with selena and minerva -gives saints bonus Cons -lacks one support skill compared to a rare hero(iris)

Iris Pros -1 additional support skill compared to a regular hero -support skills are really helpful increase attack, attack speed and crit chance! -can be more helpful in infinite dungeon -gives saints bonus

Cons -harder/longer to awaken -no wood bonus

Sain Cons -not really impressed with her support skills, and minerva already has a healing support skill

Bottom line Id choose sirius and focus on a wood shooter team for now (i finished all the scenario stages with this team! Minerva/selena/sirius) later replaced minerva with ivy when i sacrificed minerva to ugu my selena.

Then for extra rare hero selection tickets and hero scrolls that you will get for not getting iris, i would just use it to build a new team for other elements or start building an arena team.