Follies: (Papermill) Ann Miller. One of the rare times I've experienced a standing ovation during a show, as opposed to at the curtain call. By no means is her version of I'm Still Here my favorite, but as an experience in the context of the show, it was amazing.
Gypsy: Bernadette Peters towards the end of the run. I saw her in previews (not great) and much later. It was like night and day.
Caroline or Change: Tonya Pinkins
Hollywood Arms: Michele Pawk. There was something so tragically sad and beautiful about her performance.