OK, now that I've gotten my least favorite episodes out of the way, here's my ranking of my favorite Rick and Morty episodes (up to season four):
Season one: "Close Rick-counters of the Rick Kind" I don't think this is necessarily the best episode, but it's still my favorite episode of all time. The Citadel of Ricks sounds ridiculous (or rick-diculous) in theory, but somehow that episode makes it work. This show introduces so many great concepts: the Citadel, Doofus Rick, evil Morty, the evil Rick robot. It was fascinating to see a sweet, gentle Rick that got along well with Jerry as well as an evil Morty whose true motivations are still unknown. Plus, this episode was fun and hilarious to boot. It's basically the ideal Rick and Morty episode--a fun, exciting adventure that introduces an intriguing sci-fi concept and sets up a bigger story that carries through the rest of the show. I'm still wondering what Rick's comment about a "cocky Morty" was about (and I'm pretty sure the rest of the fandom is, too.)
Season three: "The Rickshank Redemption" OK, this is it. This is the best Rick and Morty episode of the entire series. The episode cleverly starts with a fake-out, then turns into an exciting, fast-paced adventure that actually shows Rick's brilliance instead of just telling us that he's smart. We get our biggest glimpse of Rick's backstory to date (who knows how much of it is true, but still), character development for Morty and Summer, worldbuilding for the Citadel of Ricks and a brilliant callback to "Rick Potion #9." At the end, Beth and Jerry finally separate, a decision that has major impacts for the rest of the season instead of resetting itself in the next episode. The insanity all culminates in Rick going on another unhinged, manic tirade in the garage that ushers in the "darkest year of our adventures." This episode also had a huge cultural impact with the now-infamous Szechuan sauce reference. I don't think Rick and Morty is ever going to top this one, which is so well-paced that it feels like it's longer than twenty minutes.
Season three: "The Ricklantis Mixup" The Citadel worldbuilding is excellent (and again, it's a concept that shouldn't work, but somehow does), but what really makes this episode stand out is how it weaves together multiple stories that seem like they're unrelated at first but come together in the final conclusion. This episode is a brilliant commentary on the issues that plague modern society (which is rare for Rick and Morty) and explores how Ricks and Mortys from alternate realities can be wildly different, which doesn't really come up in other multiverse episodes. The artwork in this episode is top notch, too. Just a phenomenal episode all around.
Season two: "Interdimensional Cable 2" This is probably the episode I've watched the most. I wasn't a fan of the first Interdimensional Cable episode, but this episode pretty much fixed all the issues that I had with it. Most of the clips were so bizarre and unfamiliar that you actually felt like you were watching episodes from another reality. "Lil Bits" and "The Adventures of Stealy" are my favorite clips. The framing device with Jerry was also hilarious and gave us a fascinating glimpse at an alien hospital (OK, it was mostly jokey, but still.) Rick and Morty has some issues with the animation, but the alien designs are always excellent.
Season two: "Mortynight Run" This episode was just an awesome Rick and Morty adventure. I loved the brightly colored alien worlds that they explored and the way Rick's plans spun wildly out of control. Blips and Chitz and the Jerry daycare sound kind of silly in theory, but they ended up being perfect additions to this episode. Plus, this episode had a lot of memorable interactions between Rick and Morty. "That's the difference between you and I--I never go back to the carpet store."
Season two: "Total Rickall." This episode is so much fun. The concept is brilliant, and the solution to the problem is actually really clever, not a dumb cop-out. The crazy characters that keep showing up are hilarious--and best of all, this show introduced Mr. Poopybutthole. I love how the animators added him into the opening sequence. Plus, the twist at the end of the episode is genuinely shocking. The audience thinks that they have it figured out and the Smith family is naively letting him stay in their lives. But nope--Mr. Poopybutthole is actually real, and Beth might have just killed him. To top it all off, the after-credits scene is brutal. "He says he's sorry that you didn't have any bad memories of him."
Season three: "Rest and Ricklaxation" I probably don't have to tell you how much this episode is a brilliant exploration of Rick and Morty's characters. What I love about it is how it doesn't go the way you'd expect. Rick and Morty become "nice" and happy, but it's actually detrimental to their personalities--Rick is a hollow shell who doesn't care about his grandson, and Morty is basically a high-functioning sociopath. The part where detoxified Rick burps and says "Excuse me" is pure genius.
Season three: "Vindicators 3: The Return of Worldender" I feel like a lot of people don't like this one, but it was a fun send-up of superhero movies (I'm saying this as an MCU fan) as well as a great exploration of Rick's toxic, codependent relationship with Morty. I mean, the entire plot basically happens because Morty said (or implied) that he likes the Vindicators more than Rick. This was also one of the rare times when we see Rick when he's hardcore blackout drunk (as opposed to his regular level of drunkenness.) "Who the fuck is Noob-Noob?" is my favorite ending line of the entire series.
Season four: "The Vat of Acid Episode" I didn't rank this one higher because I have to be in a certain mood to watch it, but it stands out because it's utterly different from any other Rick and Morty episode. This episode wasn't afraid to take risks, like setting up a basic plot (Rick and Morty being stuck in the vat the whole time) and veering away from that altogether. The long sequence with Morty's girlfriend was also pretty risky. I thought it was out of place when I first watched this episode, but now I think it adds a lot to the show. Then there's the fact that Rick's plot is so utterly cruel and brutal, even for him. The only slightly "redeeming" thing about it is that he created a way to undo the whole thing--but still, he put his grandson through an insane amount of emotional trauma just because he was starting to stand up to Rick. This episode also had some of the best Rick and Morty interactions of the entire series. "The Vat of Acid Episode" was complex, challenging and another one of those rare times where we see that Rick is truly brilliant.
Season three: "The Wedding Squanchers" I don't rewatch this episode all the time, but I liked this one because it had some good character moments like Beth finally admitting that she tolerates Rick's bullshit because she doesn't want him to leave again. This is also one of the rare episodes where Rick does something truly selfless that doesn't benefit him. We also see that Rick claiming that he doesn't care about anything is a bunch of bullshit--the way he screams when Tammy shoots Birdperson is tragic and horrifying. Plus, who saw that twist with Tammy coming? And of course--this episode sets up the best episode of the entire series.