When it comes to the best horses, there are many synonyms that one can use interchangeably with the term "top horse." For example, one could say "leading steed," "preeminent mare," or "elite stallion." Other synonyms for a top horse might include "champion equine," "premium pony," or "dominant mount." Additionally, one could use more specific terms to describe a top horse's expertise, such as "show jumper," "dressage master," or "racehorse extraordinaire." Ultimately, whatever term is used to describe a top horse, it should convey a sense of excellence, skill, and superiority.