TOS: The Cloud Minders. One of the show's extremely heavy-handed message episodes, this time about classism and labor rights. It's quite dramatically compelling in addition to expressing its ideas eloquently.

TAS: Beyond the Farthest Star. One of the more "normal" episodes of that series, but it really works for me.

TNG: Contagion. One of the most tense and action-packed TNG episodes, featuring computer malfunctions both amusing and terrifying, but also a great showcase for all the characters, and their ability to combine their talents to solve what seems like an impossible problem, to the point that it's one of the episodes that got me into Trek in general (alongside Remember Me).

DS9: Visionary. Pretty good episode of time travel weirdness, and one of my go to examples of what I think is best way to go about explaining time travel: don't explain it, just do whatever wacky shit you want and laugh off the paradoxes with a recurring joke. "I hate temporal mechanics!"

VOY: Latent Image. In addition to being yet another fascinating exploration of the rights and sentience of artificial life, with a hint of an ethical dilemma in there, I really relate to how the Doctor's trauma responses are described.

DIS: There Is A Tide. I love all of the scenes between Admiral Vance and Osyraa.

PIC: The Impossible Box. I remember that being one of the more tense and well-made episodes of the show, especially Soji's existential crisis and Picard's Borg flashbacks, although I find it hard to think in individual episodes with this one.

LD: Veritas. The show hadn't really clicked with me before this episode. I loved the whole theme about the lack of attention the command crew gives to the ensigns, and how this just adds to their problems.

I've only really seen the consensus classics of ENT, and while I have seen SNW and PRO, my favorites are all consensus favorites that get a decent amount of buzz already.

Voyager: S3, Ep. 23, "Distant Origin" is one of my absolute favs. It follows the team's interactions with a not-so-alien race and the friction in their culture between science/academia and religion. I love Voyager overall, but this episode had me on the edge of my seat.

I have real love for TNG S1E16, "Too Short a Season."

The Enterprise is dealing with a hostage crisis on a planet where the local government wants this old admiral who had negotiated a truce there decades before to come back. He shows up and it turns out he's taking experimental de-aging drugs to grow younger. It turns out that when he had negotiated the original truce before, he had violated the prime directive and given weapons to some rebels, but he told himself that he made it even by giving the same weapons to the other side, which led to decades of bloodshed.

The writing is just okay, and the old guy / young guy makeup is pretty bad, but the scene where the admiral dies while looking into his wife's eyes gets me. I also like to imagine that the ep might have originally been written with Kirk in mind as the old guy, because the whole "Well I made it fair by giving weapons to both sides" seems like the kind of cowboy insane shit that Kirk would pull and then never consider the consequences. The episode feels a little bit like it's revisiting some of the times when Kirk would do his thing and then warp off into the sunset while definitely leaving some loose threads behind.

Underrated: Oh boy, time for some takes...

TOS: This might be the hardest to pick - maybe "The Corbomite Maneuver"? It's fairly well-known, but is crowded out in a season full of classics.

TAS: Pretty much everything besides "Yesteryear" is underrated, but if I have to pick one, I'd pick "The Magicks Of Megas-Tu" for sheer weirdness.

TNG: "Remember Me" - really good episode. I think it's pretty well-regarded, but it should be better regarded.

DS9: I've always been very fond of "The Sound of Her Voice," for some reason. I don't think I'd ever seen anything quite like it when it originally aired.

VOY: I think "Counterpoint" is the finest episode they ever did, but people rarely talk about it.

ENT: Uh...I guess I'll say "Daedalus" - it does a lot of worldbuilding surrounding the transporter, but isn't one of the big "lore" episodes that people tend to talk about.

DSC: "Su'Kal". The cause of the Burn is something that speaks to the humanist core of Star Trek in a way that many people seem to overlook.

PIC: "Remembrance." The first episode of the series is nearly perfect.

LD: I don't know if the nature of the show lends itself to this exercise, but I'll say "An Embarrassment of Dooplers".

PRO: "Crossroads" - the kids arriving at a turning point, and making the kinds of dumb decisions that kids make.

SNW: "Ghosts of Illyria," I guess - this series is still pretty fresh, but this is one of the better episodes that isn't a "gimmick" episode.

Not sure if I even know what's underrated or not, considering I'm not really active in any star trek communities these days, but I'll just base these on how often I hear about them and if I've ever really had must discussion with them in the past.

TOS: I've always really loved the episode "The Conscience of the King" and I never hear anyone talking about it, really. I thought it was a decent mystery and, albeit maybe its because I was young when I first saw it, I didn't really see the plot twist of who the killer was coming. I thought the acting from Shatner, Arnold Moss (Kudos), Bruce Hyde (Riley), and Barbara Anderson (Lenore) was very good. It pretty seriously tackled some dark shit as well. Massively ballsy move on Star Trek's part to show a pretty nuanced look at the psychology of a dictator a mere 20 years after the end of WWII. I also think it's so interesting to give Kirk that piece of backstory and I find it a shame that it was pretty much retconned by never being mentioned again (at least, never that I can recall)

TNG: The season 3 episode "The Survivors" is a favorite of mine that, again, I don't hear talked about much. It's very scifi, the idea that an omnipotent, Q-like being could fall for a mortal and what would happen if that mortal was killed and someone with that much power for revenge was given the reason to take it. I like that, in the end, Picard takes pity on him.

I also always really liked the episode "The Bonding." As someone who not too long ago went through a period of grief, that episode does an excellent job exploring a lot of those feelings and how people with similar trauma can trauma bond. It also proves that Worf is actually the most shittiest person to have as a family member, considering he fights the entire episode to get Jeremy to be his brother and then we never see Jeremy again.

DS9: I always liked "A Man Alone." There's a lot of small gems in the earlier seasons that I feel get overlooked because the earlier seasons of most Star Trek shows are pretty rocky. But I think if I had to choose one, I'd say that one. It's been a while since I did a DS9 rewatch, so I'm not gonna talk in depth... but yeah. I like that one. And never hear about it.

VOY: I can't remember the name of it, but that one episode where Janeway "dies." I know that episode tends to be a hit with people who ship Janeway and Chakotay, but even outside of that I always enjoyed that episode. Again, a very scifi plot. The edition of Janeway's "Dad" showing up is pretty fun too.

Also, always loved the episode "The Raven." However, I very well may be biased as Seven is one of my all-time favorite Trek characters and any episode that dives into her backstory is going to be a hit with me. That episode makes me weep though. Little Annika deserved better. Literally fuck her parents.

Oh! I wasn't gonna list three for Voyager, but here we are. They keep popping into my brain. The episode (again, cannot remember the name) where they find Icheb's family I always really enjoy when it comes along during my rewatches.

Enterprise and onward I'm less familiar with so I don't feel I can really comment on them lol.

Voyager S1E3, "Parallax". It didn't make much of an impression on me as a kid, but watching again recently - and knowing the direction that the characters grow - it's actually a pretty compelling character-based drama. And the Maqui-Federation tension is thick here.