Any episode that focuses on Lisa really I might give a skip when doing a rewatch. Too preachy.
i think all through season 5, she's kind of a shitty character. 6-9 though? much better. she can be genuinely funny, and they expose some of her flaws, like not always being right, being unpopular, and her inability to accept that other people might be better.
lisa's rival - her status as the smartest and most musically talented kid in school is usurped by allison. she tries to befriend allison despite her own hatred of her, like she's fishing for some sort of flaw to make herself feel like the better person again.
lisa on ice - gets into a bitter war with bart over hockey. becomes super mean while competing (it's also hilarious)
lisa's wedding - badmouths her family in front of hugh the entire episode, but still loves them and wants them to be around. the ending to this episode might be secretly one of the best in the series.
lisa the vegetarian - the lesson here is not to not eat meat. any episode from 2-5 would have been about how she was right, but we're not meant to side with her. if there's any lesson here, it's not to force your beliefs down other people's throats.
lisa the iconoclast - the second time in the season, lisa finds out the right thing to do isn't always what she sets out to do. i think this is the weakest episode in this run, but going along with the coverup was a nice way to cap the episode. again, i think they would have tried to reveal the truth in the earlier seasons (like how she was in lisa the beauty queen).
summer of 4'2" - just a fucking great episode all around. lisa acknowledges she has no friends and changes herself (slightly) to fit in. bart is
way in the wrong here as jealousy gets the better of him, and she kinda snaps.
my sister, my sitter - okay, this episode is one of my least favorites from 1-9. i don't think the problems stem from lisa as much as the premise of an 8 year old babysitting other kids was too much for my suspension of disbelief. not much preachiness here though.
the old man and the lisa - again, lisa's good intentions turn out to be on the wrong side of things. ultimately she turns down the ten thousand dollars, but that's on her terms and to me, more believable because it came from her as a character and not because it was treated as the right thing to do.
the secret war of lisa simpson - i actually keep forgetting this episode exists. somehow i skipped it during my childhood, and i think i only caught it for the first time as a teenager or on dvd. it's probably the preachiest of this run of episodes. yeah, not really a fan.
lisa the skeptic - i think this is the last great lisa episode. it treads familiar ground with lisa believing too much and being wrong about convincing others that they're wrong, but it goes into unfamiliar territory when it becomes marge vs. lisa. that's a relationship that is rarely touched upon throughout the show (even in later seasons), and the way it's handled here is short, but brutal. lisa saying, 'i feel sorry for you' because marge believes in angels is pretty harsh. i think it was more shocking to me because marge doesn't even come across belligerent like homer can when it comes to expressing her beliefs. the way they resolve this at the end of the episode is another ending that's secretly one of the best (or at least one of the better ones)
lisa the simpson - lisa just kinda goes psycho when she thinks she's getting dumber. it's sort of the same behavior we saw in lisa's rival, except here she resigns herself to this fate. she gets preachy in front of a camera, but it's treated as a joke, and meant to serve her depression than to actually tell the audience something.
girly edition - once again, lisa can't stand playing second-fiddle, and tries to sabotage her rival, this time bart. the lesson here is to team up, but that immediately goes nowhere because no one cares about the lisa + bart anchor team.
lost our lisa - i kinda dislike this one. it has good jokes, but the plot jumps around from place to place. there's no lesson here. it's just a bunch of stuff that happened.
and like i said, 2-5 is a different bag. she's usually complaining about the wrongs of the world, and unlike britta from community, it's not treated as annoying or a joke (aside from the malibu stacy episode). lisa's subsitute is probably the best of this era, and i think still stands as one of the best episodes today.
season 1 is pretty awful. i hate the episode where she's sad, even though it leads to a funny scene in front of the school. honestly though, that subplot was really poor.