OOOO I had to think about this one for a bit. A lot of good stuff has happened as a result of her being the WoL, but that's more for other people and not just her.

For her, I think it's any time she glimpses the twins' growth (especially Alisaie, she's biased towards her protegé), or the little personal moments the Scions have with each other. Coffee with Alisaie in Sharlayan. Saving them all post-SHB and just getting to sit on top of Rowena's having tea and sandwiches as they recover. The dinner scene in Endwalker. Talking with Alisaie after Coils. The pre-Doma Castle dinner in House of the Fierce. Hot Chocolate with Alphinaud in Heavensward. Any time she gets to see her found family be a family, those are the fondest moments for her.