Didn't see Darmok. There are a whole lotta TNG episodes I still haven't seen, as I followed the show only sporadically. I didn't even pretend to follow Voyager or DS9, and I'm too burned out on Trek these days to bother catching the shows I missed.
I posted my favorite TOS episodes somewhere a while ago, but can't find it. Oh well. Of the TNG ones I did watch, these are my favorites:
True Q -- young intern Amanda suddenly saves the Enterprise from imminent disaster, thus revealing that she actually has Q powers! It's pretty cool to see a female Q.
Q Who? -- always nice to see Q spank the Enterprise around the galaxy, and we meet the Borg for the first time. (Although ST: Enterprise will have me believe that it was really Archer's crew that first encountered the Borg long before, but that somehow Starfleet then completely forgot about that incident. Archer Who?)
The Survivors -- lonely alien lives quietly in regret after wiping out an entire warmongering civilization in anger. Picard leaves alien in peace after telling him his crime is so immense that no Federation law exists to deal with it, or something like that. That's right, Jean-Luc, get outta there. And note to any other war-like races: don't piss off omnipotent aliens who can wink out your existence with a thought.
Deja Q -- Q is stripped of his powers. Hilarity and mayhem ensue.
The Most Toys -- Data is abducted to become part of a prized black market collection of rare artifacts. I hated that bastard collector.
Transfigurations -- a nice, feel-good Trek story. Enterprise crew befriends crippled amnesiac who turns out to be lifeform on the verge of transforming into being of pure energy.
The Best of Both Worlds -- Roland of Gilead in a post elsewhere said something like this was the Borg shown at their most disturbing, what with Picard being assimilated. After this episode, the Borg became a caricature of themselves. I would agree with that.
Galaxy's Child -- Geordi's romanticized notions of the Enterprise's designer clashes with reality when he gets to meet her in the flesh. I liked the interesting tension in their relationship and how they managed to forge a friendship of sorts in the end.
Cause and Effect -- Here we go, the Trek writers having fun with causality loops. Then there's Kelsey Grammer. The man. The captain. The legend. 'Nuff said.
Thine Own Self -- Data loses memory while retrieving radioactive material that fell onto a planet with a pre-industrial village. Radioactive stuff + clueless villagers = a bad situation. (Or maybe a George Romero Living Dead movie.)
All Good Things... -- TNG ended its run with a nice flourish. Picard zips back and forth in time in a bid to save humanity from some, uh, weird tachyon-teflon-chicken bullion anomaly thingey, with Q encouraging him on. It was only fitting to have Q in the final episode, since he was in the very first one.