Star Trek

My Ten Best Episodes of TNG:
1. Yesterday's Enterprise (S3 E15) - Often given 2nd place, I love this one because it's a fun play on an alternate timeline, time travel, the temporary resurrection of a character, and some history of the Enterpirse line. I give it first place for sheer storytelling prowess, and also, who doesn't love a Galaxy Class warship, with the miltary bridge?
2. The Best of Both Worlds (Parts I and II) (S3 E26, S4 E1) - Often given 1st place, I move this to second because, while they are great episodes, and they solidify the quintessential Star Trek villain, I have less fun with this than Yesterday's Enterprise, simply because Yesterday's Enterprise plays with so much of what we're familiar with in interesting new ways.
3. The Inner Light (S5 E25) - This episode takes the captain and tosses him into an alternate life.  It's an emotional, powerful journey of character development, and leaves a lasting impact on Picard and the audience.  Not a lot of heavy sci-fi here, just simple humanity.
4. The Measure of a Man (S2 E9) - This is classic Star Trek - a morality play, as courtroom drama, addressing tough issues.
5. The Offspring (S3 E16) - Airing immediately after Yesterday's Enterprise, this is the flipside of the coin - another morality play with parallels to The Measure of a Man, except now addressing Data's desire to procreate. A shockingly emotional journey as well, considering Data is incapable of it.
6. All Good Things... (Series Finale) - The knockdown, drag-out finale of one of the best scifi series on television, ever.  
7. Lower Decks (S7 E15) - I like episodes that take us out of our usual comfort zone.  This one throws us in with some junior grade officers, and shows how it feels to operate on a big, important starship when you're just a cog in the works doing your job.
8. Darmok (S5 E2) - Throw two characters who can't understand each other into the fire and see what happens.
9. Family (S4 E2) - Once again, taking us out of the usual and giving us the unusual.  While the Enterprise is repaired from their battles with the Borg, crew members reconnect with family, and themselves.
10. The Drumhead (S4 E21) - Another morality play highlighting the dangers of following a line of thought to its seemingly obvious conclusion, even if extreme.

Honorable Mention - Half a Life (S4 E22) - This one establishes Lwaxana Troi as a character of compassion and thoughtfulness, and from this point, becomes one of my favorite guest characters of Star Trek.  It is also a morality play about perceptions of cultural traditions.

My Personal Favorite Episodes per Season not including cliffhangers:
1. Conspiracy - I picked this one for the sheer insanity that is the episode, and the surprise ending, with a bang.
2. The Measure of a Man
3. Yesterday's Enterprise
4. Family
5. The Inner Light
6. Lessons - I'll be honest, I like this one mostly for the music. 
7. The Pegasus - I picked this one for the cool technology (and the satisfaction that Starfleet has some technological edge on the Romulans).