Sasori?
Sasori was able to kill the 3rd Kazekage, who was supposedly the strongest Kazekage in history. He had a poison what without an antidote meant certain death.
If Hidan was able to get your blood, death was almost certain. In order to do this he had to use his scythe to cut you. Sasori is similar in that if he cuts you, its pretty much over. The huge difference is Sasori has 100 puppets which equals 100+ blades. Thats a 100x better chance of hitting you than Hidan. Then on top of that he was just as durable, had the Kazekage which allowed him to use Iron Sand and he was much more intelligent.
I just don't see how you could possibly think Hidan was stronger than Sasori.