What do you think are his top 5 performances?
Hard to decide, because I like so many...
Top 5 (...actually, 6) competitive programs:
Jr.Worlds 2005 SP "Super Mario":
https://www.youtube.com/watch?v=CHLMYUpQ1vw
Worlds 2006 QR "Zatoichi":
https://www.youtube.com/watch?v=rob3ShytrQ4
Worlds 2006 SP "Barber of Seville":
https://www.youtube.com/watch?v=ZpUVnJXF2qI
TEB 2009 LP "Charlie Chaplin":
https://youtu.be/0Jt9cH01j90?t=13
NHK 2013 SP "Cotton Club":
https://www.youtube.com/watch?v=Spw1dxM-aok
Japan Open 2016 LP "Liebenstraum":
https://www.youtube.com/watch?v=M7EMnCUhQf4
Top 5 (... by 5 I mean 11) galas/cheesefest:
Japanese Super Challenge 2007 "Rooster":
https://www.youtube.com/watch?v=XQ9YC0us8Yg
Dreams on Ice 2007 "Around the World":
https://www.youtube.com/watch?v=GMuU-3oYrK4
Japanese Super Challenge 2009 "Fly Me To The Moon (Sinatra ver.)":
https://youtu.be/XusX2zPzH3I?t=23
SOI Osaka 2013 "The Last Samurai":
https://www.youtube.com/watch?v=6nrzCSHhKo4
PIW 2013 "Once Upon a Time in the West" -
https://www.youtube.com/watch?v=DJ9U7-QyHQo - It's Nobunari's own choreo!
PIW 2014 "Adios Nonino":
https://www.youtube.com/watch?v=oFxf2OAI6tE
PIW 2015 "Riverdance":
https://www.youtube.com/watch?v=mRMUG-4GwV4
SOI 2016 "Star Wars" (AKA Odarth Vader XD):
https://www.youtube.com/watch?v=PWtJx3OBmA0 (PIW version with interview about parenthood with Miki & Shizuka at the beginning:
https://www.youtube.com/watch?v=Bnp2Z_7C9s0)
The Ice 2017 "To Build a Home":
https://www.youtube.com/watch?v=_UA8BMeYc8U
Christmas On Ice 2017 "Lay me Down":
https://www.youtube.com/watch?v=z7GB7q_R5a4
SOI 2018 "L-O-V-E":
https://www.youtube.com/watch?v=YfNHhK8L2qw
Honourable mentions (competitive):
Skate America 2006 SP "Fly Me To The Moon":
https://youtu.be/RdbaVZIklUs?t=32 - a tiny wobble on the 3F, but otherwise a perfect program.
GPF 2010 SP "Storm":
https://www.youtube.com/watch?v=R7nJtpMDCYw - Minus points for terribly unflattering hairdo and pants, but this was a really nice program. It was reprised as a show program later on (
https://www.youtube.com/watch?v=vObjkudtZJc), with more transitions and much better hairstyle

.
Worlds 2011 "Grieg":
https://youtu.be/mqVlvL6-mp4?t=40 - Let's just ignore the fact that somehow Nobu managed to Zayak out his most valuable combo (and himself out of a World medal) and enjoy the intricate choreo and butter-soft jumps :') I just love the entire part around the first 3F - transitions in and the landing edge leading directly into circular step sequence.
Kokutai Taikai 2013 SP "New Moon in The Old Moon's Arms":
https://www.youtube.com/watch?v=zjWXc4Xlcng - Tears at the end

First time he landed a clean quad in the SP, just after missing the World's team due to not recovering from a leg injury fast enough. Lovely music.
GPF 2013 LP "Wilhelm Tell":
https://www.youtube.com/watch?v=Gb17EVK1SEc - A fall on the first quad, but otherwise a very nice program, especially the finale. It was nice to see him not only skate well despite his knee injury, but to find a more Zayak-proof layout and recover well after a mistake. It's a shame he didn't get to skate at the Olympics.
I also liked the "Sorcerer's Apprentice" LP, but his best performances (at Kokutai Taikai 2013 & Bavarian Open 2013) were, sadly, deleted off YT.