The best part of HP, and the bit that I think captured imaginations and has given the series any lasting appeal is just the whimsical magical world. Silly magical Britain, basically.

Even as a child and before JKR went off the deep end into transphobia, the best bits for me were the sections between leaving the non-magical world, and before the plot kicks off at Hogwarts. The actual plot itself was middling and at times forgettable. The underlying themes and their (lack of) resolution are best not thought too hard about.