Anime that need another season/remake

I really gotta disagree with you about Tokyo Ghoul. I liked season 1 a lot, but I liked some aspects of Root A better. One of them being that Kaneki actually fucking fights without crying about something for once. The only time I recall him doing that in season 1 was during the final episode. I did enjoy a good amount of the fights in season 1, but season 2 definitely had plenty of its own moments. I could never consider Root A as "horrible" or anything even close to that, but each to his own.

Though I do agree with you on Devil is a Part Timer and Noragami. I've heard rumors about the voice actors for Devil is a Part Timer saying that they're not done with it forever or something, I can't quite remember what the article said. As for Noragami, I'm pretty sure it'll be a long while before season 3 comes out (if at all), because Aragoto just finished airing last month.

A couple very worthy mentions would be Rokka no Yuusha and No Game No Life.
Rokka had one of the biggest plot twists/surprises I've seen in an anime, and the final episode itself even ended as a cliffhanger. It was a top notch anime from beginning to end. But sadly, I've heard that it won't be getting a 2nd season because of low sales in America. I still have some hope though.
No Game No Life was simply fantastic. Sora and Shiro's tactics, strategy, and teamwork are absolutely astounding and impeccable. With the way things ended, I'd say that it really needs a 2nd season. They had plans to challenge the God of the new world they were placed in, and that's something I'd really love to see. Hopefully it'll happen either this year or next year.

 

I don't really watch anime, but two of my favourites have been listed here already; Ouran High School host Club and No Game No Life.

I first found out about OHSHC when I was flicking through TV channels late at night a few years ago (it still plays to this day on the free-to-air tween network), and then decided to marathon it when a friend gave it to me. I really loved the whole anime and every character in it, but I wasn't really satisfied with the way it ended. I mean, sure it's a happy ending and all, but then what? We hear that both Tamaki and Kyoya have feelings for Haruhi and wish to marry her, but we never get to see that. I know how it ends thanks to the manga, but I really wish it could've got a second season.

NGNL is a different story, and I'm kinda on the same page as Sanc here. In the 12 episodes they had, NGNL has become one of my favourite anime of all time. The art style, the characters, the genre; everything was right up my alley. And in the 12 episodes they had, Sora and Shiro got so much accomplished! I was so psyched to watch them collect all the pieces to end up facing Tet, but hen it just ended with a black screen and writing saying something like "Let the games begin!", and that was it. This anime could have gone so far, but it didn't, and that makes me so sad. I really wish this got a second season, or at least a bit more of what we already got.

 

NGNL, The Devil is a Parttimer have been mentioned, not much left to say about those except the original series were awesome. Other series that need another season, in my opinion, are WataMote, Bokura wa Minna Kawaisou, Danmachi, Haikyuu!!, Sekai Seifuku, Haganai and Ao no Exorcist.
Haikyuu!! and WataMote should be pretty obvious. I'm up to date with the manga of both and the way things are going with HQ!! and seeing how popular it is and how much merchandise and stuff it's selling, we should see a second season in time, but it'll probably take another year or two. WataMote is just consistently fun, would be nice to another season, but I'm good as long as the manga continues.
Danmachi and Ao no Exorcist were both solid series and were both pretty popular as well. I'm especially surprised AoEx hasn't gotten another season yet as the manga is still consistently coming out and it's been 5 years since the end of the first season. Danmachi is more understandable as the manga doesn't even cover the entire series yet and the light novel is barely ahead. Would be nice to see new season of either, but I crave AoEx more >_>
Seeing as Sekai Seifuku has no source material because it was produced only as an anime, it's understandable there's no second season yet. The series' start and ending did hint it was only the beginning of the story, but since the first season started just 2 years ago and it wasn't all that popular hopefully it won't go to waste. Having an unfinished story is too annoying.
Bokura wa Minna Kawaisou and Haganai are both light romcoms, even though they have different kinds of source material. Bokura wa Minna Kawaisou is originally a manga and Haganai a light novel. The light novel series of Haganai has ended, so I think it would be nice if they gave the anime a nice conclusion as well, the one we got in the second season left we with a sour taste and it felt slapped on, ruining an otherwise wonderful series. Well, not ruined, but it was kinda meh. Bokura wa Minna Kawaisou was a little more lighthearted and the manga is still going on so I wouldn't be surprised to see another season of that, would be nice.

 

I feel like Log Horizon needs another season, but apparently it ran out of the source material, so that would need to be continued first....

 

Medaka Box needs to at least cover the 3rd arc, since it's pretty much guaranteed to sell, considering that Kumagawa Misogi, the most popular character in the series, is in it. And yes, I'm sure that just the fact that Kumagawa would appear is enough to make it sell. Medaka Box really starts during the 3rd arc, since not only Kumagawa gets introduced, but also Ajimu Najimi, a woman who only has 12,858,051,967,633,865 different skills, and Kuudou Hinokage, who is so strong that people subconsciously block him from their senses and memory after meeting him. Medaka Box also really excels at character development, but it happens mostly during or after the 3rd arc.

Toaru Majutsu no Index is another anime I'd like to see getting another season too. I haven't read the LN, simply due to fact that I don't like reading books, and the manga is nowhere near.

Then there's Senyuu.

 

NGNL has been mentioned before, so I don't have to mention that one.

Second of all, Bobobo bo Bo bobo needs a new season!
Well, a new series actually. Shinsetsu Bobobo is the manga sequel, but I'd love to see them turn it into anime since I enjoy seeing the jokes more than reading them. Too bad Bobobo is from (let me google that) ..2001? Damn, I need more Bobobo!

 

Well, obviously we all agree on NGNL, but I haven't seen anyone mention Is It Wrong to Try And Pick Up Girls in a Dungeon? yet. Despite the name, it's actually a very good story, though the MC-

nah, not gonna spoil it. I was surprised to see that Bell was voiced by the same actor as Kazuto Kirigaya, so that was a nice touch.

I wouldn't mind another season of Arpeggio of Blue Steel, either, now that I think on it...

 

My main ones have already been said. Studio Bones needs to Make a Soul Eater Brotherhood or something, Log Horizon (waiting patiently for new source material for it), NGNL (I really hope the plagirism thing doesn't kill it) and Devil is a Part Timer (THE FREAKING KID!!!)

However, there are a few anime that I feel need a sequel other than these as well. Acchi Kocchi was a very, very cute Slice of Life that had quite unique and quirky characters. I know that there is more source material, and I just need more of Tsumiki Miniwa in my life. It's just a very, very cute anime that I enjoyed a bit more than Lucky Star (must watch Is The Order a Rabbit?)

Akatsuki no Yona. A give no f***s that it's a reverse harem, it's an amazing fantasy story that had beautiful characters and a Shoujo heroine that isn't a useless character. Seriously, Yona-hime becomes such a badass in one arc. I know there is more to the story, and I need to see more!

Finally, Puella Magi Madoka Magika. After the movie, it feels like there is a new story for Urobuchi to explore with Sayaka being the only one who remembers the former world. It would be an interesting world to see, especially the interplay between Homucifer and Sayaka. I hope the rumours of a new movie aren't true and it's a series, because it feels like its would be like Charlotte's last episode, rushed and could've been drawn out into a much more interesting sequel series.