I think
Junia goes best with
Iris and
Alba, but
Beata is my favorite of the 3 choices.
And I would definitely combine drastically different popularities. It's the way the names themsevles fit together that's more important to me. I actually find it really interesting when siblings have names quite mixed in commonness, as long as they sound fine together.
Of those groups I like
Edmund Bruno,
Marius András, and
Caspar Leopold best.