My advice - Do not go with anyone's "Top 10".
My girlfriend asked to be introduced to TNG after I mentioned the Edo during a conversation. So her first experience of Trek (after Abrams) was the widely riled "Justice".
She loved it! The campness, the idea of a culture that live for pleasure, even Wesley "We're Starfleet officers..." line! I thought "Great, wait until you see this" and showed her "Tapestry". She fell asleep
She did not have the "backstory" to feel anything for Picard or Q, so an episode widely considered one of the best meant nothing to her.
We're now watching them in order and we're up to mid-season 3. She loves it. Perhaps not as much as I do, but she see's it as an insight to my childhood and can see how it has shaped my morals and thoughts. She is convinced that Picard was my childhood role-model. Perhaps she is correct.
My point is that different folks like different things, and an episode we may think to be great will not be so great to someone else. I love the political episodes such as "The Defector" or "Sins Of The Father", these send her to sleep and she likes the campy ones that I hate.
It's nice to do something you enjoy with someone you love.
Have fun!
Salient points for sure... "Tapestry" is certainly a favorite of mine, but it would have the same effect on a newbie as would showing them the DS9 finale or the 3rd season finale of "Lost" - it would have no resonance for the newbie.