I’d say The Inner Light is almost universally considered the greatest TNG episode, although there are other great ones.
I in particular enjoyed The Measure of a Man, The Drumhead, The Chase, Who Watches The Watchers, Yesterday’s Enterprise, The Offspring, The Best of Both Worlds, Darmok, Chain of Command, The Pegasus, Lower Decks, and All Good Things.
Almost certainly the worst episode is Masks (or maybe Shades of Grey)