The Lion attacking the weird puppets that came after him and his friends. Without this moment of courage, they'd all have been dead, or at least captured by the witch.
The Emerald City color change dance scene. It's flashy, flamboyant, and colorful.
The TV special
The Cowardly Lion dancing with the poppies until he ties them up in their own vines.
The Emerald City Vogue scene. It was one of the most unexpected and most talked about moments of the 2015 production.
Harvey Fierstein has stated in multiple interviews that he hoped not to make Dorothy seem like a "victim", and tried to give her a more proactive role than some previous adaptations of The Wonderful Wizard of Oz did. For example, Dorothy doesn't need anyone to prompt her to exploit Evillene's weakness against water, unlike in the play and movie of The Wiz. Dorothy just grabs a bucket, dumps the water all over Evillene, and watches the liquid destroy the witch.note This does indeed hew a little closer to The Wonderful Wizard of Oz, in which Dorothy doused the Wicked Witch without anyone prompting her. Except, Baum's Dorothy didn't know beforehand that this would melt the Witch, and only wet her in an attempt to retrieve the Silver Slipper she stole.
The costumes were all pretty amazing too. Glinda's glowing dress, the green citizens of Oz, the terrifying Winged Warriors and Kalidahs. The Scarecrow was so well done he bordered on the Uncanny Valley. The costume designers have said they wanted to look to be more film quality as opposed to stage quality. It shows. They eventually won an Emmy Award for Outstanding Costumes For A Variety, Nonfiction Or Reality Program - a mere three months after the main costume designer, Paul Tazewell, picked up a Tony for designing the outfits of Hamilton.