Ask and I shall deliver this is Haikyu character ranking.
Just a disclaimer before I start, Haikyu at this point is on the verge of a 5th season and I only recently started watching it so expect this ranking to be revisted in the future as I add more characters and change the scores as I continue watching.
Shoyo Hinata
The fun ball of energy that is a little over done in this genre, he looks weak but is backed up by some exceptional skills. He's enthusiastic but easily becomes nervous. He can perform impossible feats but is a moron. It's hard to dislike him but he's hardly memorable.
Tobio Kageyama
A bad tempered player who is quick to criticise his teammates on simple mistakes and not being able to keep up with him which actually causes his old team to abandon him, his redemption is well done and I can see myself liking him more in the future.
Daichi Sawamura
The captain actually acts like a captain, I guess they do exist. He's not that remarkable but it's nice to see someone down to Earth and actually command respect.
Koshi Sugawara
The overly nice helpful guy is already looking like he's going to be a wasted character, prove me wrong anime.
Ryunosuke Tanaka
Currently my favourite character, there's plenty of room for a boisterous macho hot blooded character in a sports anime and he fills that role nicely.
Kei Tsukishima
Last character I'll rank for now, I'm on the fence about this guy as he's introduced as a bit of a smug bastard but then he now seems bored with the situation in front of him.
Scores for now
Shoyo Hinata: 7.2/10
Tobio Kageyama: 8.0/10
Daichi Sawamura: 8.0/10
Koshi Sugawara: 6.5/10
Ryunosuke Tanaka: 8.8/10
Kei Tsukishima: 6.2/10
