Definitely Uta from Tokyo Ghoul. His mysterious nature and his skills as a mask - maker would bring a lot of intrigue. Also, Haruka Nanase from Uta no Prince - sama could be interesting. Imagine his pure and kind - hearted personality being exposed to the dark and dangerous world of Tokyo Ghoul. The contrast between them could create some really engaging storylines.
Sebastian would be really interesting. His demonic nature and his ability to adapt to different situations in 'Black Butler' would make him stand out in a crossover. He could use his skills to either help or manipulate the characters in 'Tokyo Ghoul'. His loyalty to Ciel in his own series could be contrasted with his new relationships in the 'Tokyo Ghoul' world, and it would be fascinating to see how he uses his powers to deal with ghouls.
One possible plot could be that Uta, with his unique mask - making skills from Tokyo Ghoul, gets involved in a situation where he has to create a special mask for a character from the Uta no Prince - sama world. Maybe this mask gives the Uta no Prince - sama character some special powers related to the ghoul world, like enhanced hearing or the ability to see in the dark. And then they have to navigate through both the music - filled world of Uta no Prince - sama and the dangerous world of Tokyo Ghoul together.
Naruto and Kaneki would be a really interesting pair. Naruto is all about hope and never giving up, while Kaneki has this internal struggle between his human and ghoul sides. Naruto could help Kaneki embrace his duality more positively and Kaneki could show Naruto the darker side of a world where survival is not as straightforward as in the ninja world. Their different powers, Naruto's chakra and jutsu and Kaneki's kagune, would also make for some exciting battle scenes and strategic combinations.
I think Luna from the Loud House would be really interesting. She has that rocker vibe which could mesh well with the spooky and unique nature of the ghouls. And then there's Spectra Vondergeist from Ghoul School. She could use her ghostly abilities to have some cool interactions with the Loud kids. Maybe she could play pranks on them that are more friendly than scary as they get to know each other.
Rize from Tokyo Ghoul and Sirene from Devilman would be an interesting pair. Rize is a very powerful and somewhat unpredictable ghoul, and Sirene is a demon with her own motives. They could either be at odds, constantly trying to outwit each other, or they could find common ground in their pursuit of power. Their interactions could be full of tension and mind games, which would make for an exciting part of the fanfiction.
Todoroki from My Hero Academia could be really interesting. His dual - quirk nature could have some really cool interactions with the ghoul powers. He could use his ice side to counter the heat - based attacks of some ghouls, or his fire side to fend off cold - blooded ghouls. His complex backstory could also add depth to a story set in a crossover world.
Definitely Thor and Tsukiyama. Thor, the god of thunder, with his powerful hammer, and Tsukiyama, the flamboyant ghoul. Tsukiyama's refined tastes and his kagune skills could be paired with Thor's brute strength. They could have some hilarious banter as they fight side by side against enemies. And also, Black Widow and Touka could be a great pair. Black Widow's spy skills and Touka's street - smart and combat - ready nature would make them a formidable duo.
Kaneki and Zero could make an interesting pairing. Kaneki has his inner turmoil with his ghoul side, and Zero has his own battle against his vampire nature. They could bond over their struggles to control their 'dark' sides and their determination to protect the ones they care about.
Kaneki Ken is definitely one of the most interesting. His transformation from a shy bookworm into a half - ghoul with complex emotions and moral dilemmas makes him a very engaging character. Touka Kirishima is also great. She's a strong - willed ghoul who has her own code of ethics and is not afraid to fight for what she believes in.
Tsukiyama Shuu is quite a character. He has his own unique sense of 'taste' when it comes to ghouls and humans, and his complex personality makes him stand out. Also, Touka Kirishima is interesting. Her relationship with Kaneki and her role in the ghoul community add depth to the story.