I mean Fate Stay Night had THREE Greek Servants, One British, One Irish, One Japanese, One In-Universe Hero and a Major appearance from a Babylonian. If anything was getting favored there it was the Greeks, but otherwise there was good variety. Man even had the restraint not to unnecessarily push the only Servant who was solely HIS creation (Archer does lose in all three routes after all). Admittedly I would veer more towards fiction than real life people and myths.