It’s terminal specific as it uses kitty’s graphics extensions but it looks really IMHO.
https://sw.kovidgoyal.net/kitty/kittens/diff.html
* colordiff -y: https://www.jefftk.com/colordiff-y-example-simple.png
* icdiff: https://www.jefftk.com/icdiff-example-simple.png
icdiff also makes better use of horizontal space.