I keep re-reading the manga, I love it so much! The characters and their relationships are so cute (especially between Hinata and Kageyama, or Kageyama and Aikawa's rivalry).
The reason why I like this manga so much, is because it's a more realistic take on the sport. It shows hardships and gives them a reason to grow stronger, their improvement and how talent is a big deciding factor, how height in volleyball can really make the game more different and the opponents more tougher, etc etc.
Concerning Betmen's comment:
First of all, I am not discrediting your opinion by any means (that you find it just good). However, I am discrediting (a little) the facts that you gave for your opinion - FACTS. I apologize if this offends you somehow, but your comment lit a certain fire in me that I just felt the need to add my own 2 cents.
Of course there's going to be a lot of repetitive movements in sports - not just volleyball. This isn't some random action manga where characters can use their body freely to either kick, punch, elbow, slash, or even use magic to destroy/hit objects or people. There's a certain way people play volleyball and that's either to: pass the ball, set the ball, and spike the ball. However, volleyball is also flexible enough where a person can use any part of their body to do all of that (spike, pass, set, etc.), as long as they don't use an open hand below a certain level of their body.
Let me just point out, this is all with their BODY. They can't just magic a sword in the midst of a game and wave it around, hoping to catch their opponents off-guard or strike the ball. There's also a certain set of rules to the game that limits the players and removes a few options they can do, i.e. open-hand passes, illegal screening, touching the ball twice (not including serve receives first passes), etc.
So yes, sports will have a lot of repetitive movements. Despite this, it's still exciting to watch/read or participate in. You should try a sport, if you haven't.
Plagiarism: the practice of taking someone else's work or ideas and passing them off as one's own. [Making Haikyu not a plagiarized version of slamdunk, seeing as they both have a different set of characters, schools, dialogue, etc.]
Let me tell you one thing: there will never be an original character, idea, or book aside from the very first work of art/literature/movie, etc. that it's been seen in. This includes both Slamdunk and Haikyu. In the past, there has probably been many characters that are similiar to Nishinoya or Miyagi. There has also been many relationships that are similar to the rivalry between Aikawa and Kageyama - way too many, in fact. So, I don't see why you think this is plagiarism. They might be similar, but there's a clear difference between volleyball and basketball.
Once again, I apologize if this offended you, but it just bothered me.
TLDR; There will be repetitive movements in SPORTS - try watching a sports game. This isn't plagiarism, there's just only A FEW similarities between a few characters/relationships, other then that, the dialogue, setting, etc etc is totally different.