1039: Dry Ice. Great harmonies and a great guitar solo.
Kerplunk: Words I Might Have Ate. I really like the fact that it's an uptempo song with acoustic guitars.
Dookie: In The End. Very short and very good.
Insomniac: Stuart And The Ave. Possibly the most underrated song of them all. One of my absolute favourites.
Nimrod: Haushinka. That bridge is my favourite part. Awesome song to play very loud through the stereo.
Warning: Macy's Day Parade (I'd like to say the whole album though). My favourite Green Day ballad. Such fantastic song, should end concerts instead of Good Riddance if I could decide.
American Idiot: Whatsername. Unjustly forgotten among the other songs on AI, for me it's the best song of the album alongside JoS
21st Century Breakdown: ¿Viva La Gloria?. My favourite track on the album. I especially love the "you dirty liar" part and the "Gloria" shout.
It's a bit too early for me to judge which song of Uno that is most underrated.
Fashion Victim has been played live http://www.greendaycommunity.org/public/... (if it was what you meant and not Deadbeat Holiday) :
Oh yeah, I knew that, i mean in the way like never played live meaning hardly played live, like you would say walking contradiction is never played live, it HAS been played live but hardly ever, and not in a long time.