It's so hard!
Although I went for Deep Space Nine in the best series thread I have to admit TNG had a great finale. A fitting end to a great show that made Trek live again. What You Leave Behind comes in a close second but All Good Things... had it all.
The poker scene where Picard joins the rest of the staff...beautiful...perfect ending.
"The sky's the limit..."
It so is....that really summed Trek up for me that line.
Spes aspera levat - Hope lightens difficulties.