Yeah, it's 6 years old, but I'm answering anyway.
Definitely "Trials and Tribble-ations". I love "Darmok", but T&T was a fantastic effort, and is easily one of my favorite tributes to the original series. Plus, this was before the cleanup project, and everything looked so spiffy and new, I love it. Also, Dax.
“I've noticed that about your people, Doctor. You find it easier to understand the death of one than the death of a million. You speak about the objective hardness of the Vulcan heart, yet how little room there seems to be in yours.” - Spock, The Immunity Syndrome
Leonard Nimoy: 1931 - 2015