Its been three decades that I watched "Star Trek The Next Generation".... Yes DS9 was lot more exciting and The Original Series was more glamorous and profound. But TNG's preparation and the philosophical might astonishes (well too strong a word ... it astonished me in my teen ages but still close) me still today.
Season 2: Episode 15 has always made a profound impact.
"What will Picard do?" : Riker giving advise to Wesley on being a leader
"Data !! Your Whisper from the dark has become a plea; We can not turn our back" : Picard where he goes on to violate prime directive
"One of my officers;; One of my friends was troubled I _had_ to help" : Picard dismissing Data's apologies
"Remembrance and regrets, They too are part of friendship. And understanding that has brought you to a step closer to understanding Humanity!!!" : Picard to Data
Fun fact: I have always mostly been mildly drunk when I watched Star Trek TNG S02E15 :-) (except for my teen days ofcourse :-O :-O)