I don’t think I have a favourite butterfly, but I love the bright colours of the peacock butterfly, especially contrasted with its shimmering black underwing.
I attended an interesting course titled Origins of Colouration in Invertebrates – Pigment and Structure which was organised by FSC Biolinks as part of their Virtual Meet Ups series. It’s been a really fascinating series on a wide range of topics, and they’ve been making the recordings available after the fact on YouTube, so it’s well worth checking them out.