well, i don't think you could go wrong with any one of them. it really depends on your needs. the trick is learning how to use them, and that's hard. i'm looking into getting the sigma unit for my canon, i'll let you know whenever i get it. off the bat though, i can tell you that the sigma flash has poorer (not by much) construction quality than any of the nikon or canon flashes. but they are definitely just as good power and feature wise, not to mention significantly cheaper.