Tied between Hashirama and Nagato. I like Nagato because of his personality and attitude, he just wants peace but he's malleable. In the end, he was a nice guy. I like Hashirama because out of all of the characters in Naruto, we share the most in common: eldest sibling, humorous (you don't see that many "comedians" in the series), perverted (probably passing it on to Hiruzen), etc. Both Hashirama and Nagato are powerhouses too, which makes them even cooler.
EDIT: And I'm just gonna guess that your favorite character is Tobirama :eww:.