Tonari no Seki-kun

Both shows entertain with frivolous and random comedy. Nichijou has full episodes and more characters while Seki is shorter and, so far, focuses on only two people. 

Comedies about boy and a girl in school setting, sitting close to each other and teasing/pranking the other to get away with boredom. In Seki-kun the boy is the one teasing most of the time, in Takagi-san it's the girl. 

Two high-school anime which follow a male student as he endeavours on comical mishaps. Although Tonari no Seki-kun doesn't follow a perfect student and he seems more quiet and isn't acknowledged by the whole class: Yokoi acknowledges Seki-kun in a similar way that Sakamoto's class see's him. Both of the anime are episodic, however knowledge of the previous episodes is useful while watching the anime. 

Both consist of really funny shorts with unexpected and overly dramatic gags. Some of the episodes are philosophical in a sense dealing with people, problems of society and emotions. Both are set in a school environment. 

Both are hilarious gag anime with school setting. In both series characters come up with very ingenious and, well above all, rediculous ideas. If you liked one check the other, too! 

Roles are reversed, but the seat neighbor is always doing weird things Similar animation styles and pacing Both oddballs have the window seat, with the wingman on the inside  

The over-the-top execution of an absurd situation is carried out the extreme in both Tonari and Gintama. The Tonari manga has better artwork. 

For slice-of-life shows, Tonari no Seki-kun and Azumanga Daioh take it to a level of fascination with its small, yet colorful cast of characters. Innovative ideas about simple school life are transformed into absurdities that will draw in your attention. The dialogues spoken have the strength to bring attention toward both what's happening and the characters themselves. And because both series take place in a school life setting, you'll expect plenty of activities going around. 

Both are about girl being frustrated with clueless boy 

Both are about a man/girl who has an annoying neighbour who only plays around all the time. He/she always tries to stop him but only ends up mixed in the nighbours games. Both have short episode(s). While Tonari no Seki-kun is setted in school, Tonari no Yarou is setted in town. 

Not only are the titles similar,but the atmosphere as well! ~Both stories take place in a classroom. ~both have the main charecter (female) sit next to the main male,who is a little out of the ordinary. ~also the main females of both care about learning while taking intrest in their weirder male counterparts! even though tonari no seki-kun is shorter,both are great anime to watch if you enjoy anime shows with a slight comedic twist. 

Both are lighthearted, slice of life comedies. There is a lot more to Gin no Saji as far as plot and characters, but I think their sense of humor is very similar. But I think if you like Tonari no Seki-kun, you will definitely enjoy Gin no Saji as well.  

- a girl who has a very strange classmate neighbor - no one else can see what he is doing except her - she follows/accompanies him on his ventures - same type of humor 

Hilarious and slice of life. Very off-the-wall humor that matches this in oneshot pieces. 

Both shows are comprised of short little skits, but most importantly share a light-hearted tone and feature endearing characters which never failed to put me in a good mood.  

Both are short comedies about character's daily lives. 

Both have short, entertaining episodes depicting everyday situations. Relatively cute. 

Well, this is my first recommendation. And why I recommend this anime, even I don't know. Initial D is similar to Tonari no Seki-kun because of Takumi and Seki. I can't help it, but whenever I see Seki-kun, I see Takumi doing all sorts of crazy things in the classroom. When Takumi is spaced out he actually is doing what Seki-kun REALLY does on his desk! They both don't talk often, and make the same faces (Takumi spaced out, Seki-kun 'Killing Time' face). Both don't like losing. Also, Yokoi reminds me of Itsuki, they always look up to Seki(Takumi) and speak most of the time. -Vortrex 

If you like comedic tension between a girl who follows the rules and a boy with a wild imagination, both of these might appeal to you. 

Both are hillarious comedy shows with elements of parody and a school setting. They both feature over-the-top absurd humour as well as other anime references. Seki-kun proves that not only Sunrise can do it right! Female protagonists (Rumi Yokoi and Ichiko Sakura) look alike and both are voiced by Hanazawa Kana. Despite absolutely different personalities their inner monologs are essential parts of both shows where they can easily change their attitude from being overly caring to extremely ferocious. Good laughs are guaranteed if you watch each of the shows. 

Hiro Shimono plays the main roles in both series. One series takes place in a school setting. Our main comedy duo in this series are Seki-kun and Yokoi. Though Seki-kun does not talk but his mastery of killing time is entertaining. Yokoi tries to stop him from disrupting class time but fails. She gets involve with his shenanigans. The other one takes place in a fantasy world. Our comedy pair here are Alba and Ros. Alba gets the short end of the stick and is constantly joked upon XDD. Short episodes filled with comedy and you would laugh constantly. If you love Hiro Shimono's comedy side then I recommended both series to you.  read more 

-Both are short -Both involve a guy and a girl to which they are close (take that as you will) -if you were to take their relationship as a manzai routine, one of them is the tsukkomi(stright man), and the other is the boke (idiot) -both are very cute and enjoyable to watch, especially as an in between from serious anime -both have an OVA -both definitely should get more episodes 

They are both short comedy series that are about students coming up with random stuff, just Seki-kun plays alone during class and in Gakkatsu the whole class takes part in the discussion. 

Both consist of funny slice of life shorts, about school life. Both have some romantic interests, but nothing seriously romantic, no drama. Both are funny and lighthearted. 

- both have Hanazawa Kana as main heroine and cute OP singer - both stories about school girl sitting next to a classmate who has strange features (Shiraishi is almost invisible for others, Seki just can't study so that he does anything except sticking to lessons) - both light and cute comedies though Kubo-san wa Mob wo Yurusanai is more romantic 

Both are short animes (4 min per episode) that put longer animes in shame. 

These two shows share a number of similarities: they are both short, gag anime and are both set in school. Both protagonists are also often at odds with their surroundings. 

Both anime revolve around the same concept of simple or well-known games turning into something ridiculously unexpected. Both are ingenious and innovative, the approaches differ though: classroom minimalism in Seki-kun versus fantasy oversophistication in NGNL game-world. In other aspects the two have nothing in common except both are extremely funny comedy shows. 

Both of them are romantic comedy anime where one of the characters almost never speaks, (in this one it's the boy, in that one it's the girl), and because of that the one that does speak has a very difficult job figuring out what the other is thinking.  

In both animes the main characters are "described", they are seen through the other eyes not for what they really are. The other characters have more scenes/speaking than the main characters themselves. In Tonari no Seki-kun , Seki is always watched by Rumi Yokoi who is her classmate; in Handa-kun, Handa is always watched by the "Handa-force" ( his four classmates). 

If Tanaka-kun is the master of listless, Seki-kun is the master of killing time. Seki-kun is probably the complete opposite of Tanaka in terms of behavior. Nevertheless, both main characters have in similarities to be both unconventional in their daily school life, which makes it a joy to watch. The main characters are the type that will make you both satisfied and grin from ear to ear! They are the perfect match of unconventional comedy in a school setting! Plus great ED and OP.