Hellsing Ultimate is what hooked me into watching anime. There is nothing quite like it out there. Not much in terms of story, most of the show takes place during a single night. It is carried by characters and visuals. Animation is absolutely gorgeous, every frame is like a painting.
The original Hellsing was literally the first two episodes of Ultimate stretched into entire season. Plus something about werewolves, I dont remember what that was about. I think it was just another Nazi transformation plan, the same as artificial vampires. I did appreciate the character stuff with Seras thought. And the OST was the bomb, really wish they used it in Ultimate.
https://www.youtube.com/watch?v=HOD2DVq1r60