shodai: able to control biju's, mokuton (only one who can use it with yamato) founded konoha, impressive feats but not that cool in my book.
nidaime: brother of shodai, very good with water element. I think he is the coolest hokage because of his water element and because of his appearence @oro VS sandaime
Sandaime: old geezer, dont like him that much as a character, though I think he is the strongest as seeing him battle orochimaru
Yondaime: Very impressive, youngest hokage so far(?), very cool jutsu (hiraishin) and I really like his design alot.
Godaime: Don't like her at all, not even her looks -,-
for me Nidaime and Yondaime are nr1 and 2 but when it comes to facts and who is the strongest I have to go with sandaime