It's a complicated subjective topic, I don't think you necessary need to separate two categories as often you could combine foot fetish, stockings and office wear.
In any case if you are chasing popular trends then probably the longest lasting and most successful is Kemonomimi, i.e. characters with animal characteristics such as cat, fox, etc. Just see for example the vast majority of the most popular running virtual youtubers today are Kemonomimi, such as Gawr Gura, Inugami Korone, Nyanners, Kiryu Coco, Ironmouse, etc. None of these very popular characters are just regular humans.