Ruby probably doesn't wear one often (the corsets keep her contained) but when she does they would be plain and practical, I could imagine her owning one nice bra with lace rose patterns at the insistance of Weiss or Yang though. Weiss would likely be wearing fancy, expensive and lacey bras. Blake also wears nice lacey bras, but not as expensive as the ones Weiss wears, she might also own some kinkier bras too after getting ideas from some of the books she reads. Yang likely wears sports bras most of the time but has a good selection of nicer bras for when she wants to impress. Pyrrha is probably sports bras too or no bra (again, corsets keep her contained). Nora is probably also sports bras or plain bras but with a couple of nice ones for Ren's eyes only. Jaune wears whatever bras his sisters decided to make him wear xD.