Tough to pick just 5, but I think I would have to go with:
--Mirai's FS
--Bradie's FS
--Tarah & Danny's SP / FS
--Nathan's SP
--Grant's SP
Honorable mention: Jimmy Ma's rather interesting choice of SP music, Stellato & Bartholomay, the Knieram's quad twist, Cain & Leduc, Hawayek & Baker FD, Darlene & Peter Cain at the boards.
Hope for the future Pooja Kalyan's silver medal performances, Camden Pulkinen, Tomoki Hiwatashi's FS (and the audience reaction), the Parsons.
Angela Wang SP
Ross Miner LP
Adam Rippon SP
Cain/LeDuc LP
Hubbell/Donohue SD/FD and overall WIN!
Honorable mentions: Mirai's LP, H/B SD/FD, Nathan's SP, Alexander Johnson's SP, Timothy Dolensky SP, Sean Rabbitt LP.
Other noted things I loved: Ryan B and Angela W just being carefree and silly almost always. Raf dancing when Adam got his SP scores.
The whole atmosphere that reminds me that of all the competitions I've been to and in, Nationals is always best.
Mirai everything & making the Oly team
Ross SP/FS
Kaitlin/Jean-Luc FD
Shibs SD
Madi/Zach FD
HM: Bradie's mental toughness, Karen's both programs & making Oly team, Nathan's FS, Jason's SP/FS despite the jumps, Grant's SP, Kaitlin/Jean Luc SD without twizzle error, Sean's FS & joy of skating ETA: Parsons doing well in their senior Nationals debut