But the #1 episode ever is hands down "Bread and Circuses." Spock lays out the very real slavery under which we all labor today, verbatim, without irony or obfuscation. Seriously, check it out.
It also has the most intense "human" interaction between Spock and McCoy. There's the redemption of the fallen in the aptly named captain "Mericus," suggesting America has the chance yet of removing the yolk of slavery, that which we call "social security" and related forced government pestering.
I challenge anyone to watch this episode, and pause it and ponder Spock's words when he explains wage slavery... then tell me it's not the best message Roddenberry and Coon ever penned.
PS I'd not include "...Tribbles" on the top 5 list, probably not even top 10...
