Taylor is the hardest hitter in the league. First of all, he has a ridiculous combination of size and speed. He is built for the big hit. Playing safety, he can get a huge run up on guys and demolish them with a combination of speed, power, and size. Also, he has one of the nastiest demeanors in the NFL. He wants to lay guys out and make them not want to get up. He hits consistently and he hits big.
The only player I could see an argument for is Shawne Merriman but he plays linebacker so it is harder for him to get big runs on guys. Dawkins is aging and not the hitter he once was. He's still good but even in his prime I don't think he could match Taylor. Sanders is pretty small but he can still lay guys out. Still, not on Taylor's level. Williams can really lay big hits on guys but I think Taylor does it more consistently.