I remember really liking Encounter at Farpoint when i was a kid
Rewatching it more recently, I realized Diana's "PAIN! I FELL PAIN!" was her sensing the audience's reaction to the horrible episode
Like... It had a single episode worth of good episode in there but they left the other half in that should have hit the editing room floor
ETA: I had to look up what season 5 episode 2 is, and yes, that's an excellent representation
I'd argue that the second pilot of the original series, "Where No Man Has Gone Before" is also a excellent overall introduction to Star Trek: cerebral rather than action oriented, the focus on the people and their relationships both with each other and their own humanity, asking questions of the audience to make us think, solid message ("absolute power corrupts absolutely")...
But definitely skip the original pilot, The Cage, in its standalone form. Watching that, we were damned lucky it didn't get shitcanned fully right then and there