I’ll one-up the Osmonds with the Cowsills, who could be very good. The real-life inspiration for the Partridge Family series (and the Osmonds too, I’d guess), they were dismissed as bubble-gum by those who would be cool. And they were sometimes bubble-gum, but they could also do what I’d consider advanced baroque pop as well as anyone. No time to hunt down the hidden gems on YouTube today, but they had some very good songs (and plenty of cheese) in addition to their hits. Below is a live-TV version of their first big hit, preceded by the studio version for reference. Note how well they nail their vocal harmonies live. It’s a pretty amazing feat.