I've been rewatching TNG, so if I were to give a "best of" from the first two seasons I'd say:
In airdate order:
Season 1:
Justice
11001001
Season 2:
The Child
The Schizoid Man
The Dauphin
Time Squared
The Icarus Factor
Manhunt
The Emissary
It may not be exactly what you're asking for, but in my view the essential episodes to watch are the ones that highlight the strengths of the series. In my humble opinion, the episodes I listed above do that very well!