Not sure if this is considered a classic EQ yet, but I love the way the Mäag EQ-4 sounds. Great for adding some top-end sheen/sparkle.
A FAT channel XT emulation that models this plugin would be great, with the famous "air" band on this plugin.
UAD have an emulation out already: https://www.uaudio.com/uad-plugins/equalizers/maag-eq4.html
But would be amazing to have one inside FAT channel XT.