There is a lot to be said for darius. He has the economic power to expand, starts with animal husbandry within easy reach and can grab archery fast if there aren't horses. His economic power and UU allows him to rush/choke 2 AIs and still win lib. That is saying something.
Still, without horses, he's not so hot, and he is a long shot from bronze working, so maybe not the second best.
I'm a huge fan of bulb rushing engineering (or at least keeping the option open) so Suleiman is one of my favorites.
Willem's traits are amazing, but he lacks UU or UB of consequence. (Dikes are great, but too little too late)
Augustus and Julius are boss.
So top 5 in order:
Darius
Suleiman
Willem Van Orange
Augusts
Julius