This one is more tough for me, as these were all the first non-Stegosaurus Stegosaurs I knew about (I’ve known about Stegosaurus practically since birth).
Tuojiangosaurus (2015 or 2016)
Dacentrurus (2016)
Wuerhosaurus (2017 or 2018)
Kentrosaurus (2017, didn’t properly know it by name until 2018 or 2019)
I learned about Gigantspinosaurus, Chungkingosaurus, Hesperosaurus and all the others post-2021.