From the horse's mouth-

"Kam Chancellor right now is as good as any safety that’s played in the game of football,” Lott said. “It’s hard for me to say this, but there was only one guy that I know that’s better and that’s Kenny Easley. He was defensive player of the year and best player to play the safety position, ever. He is getting to close to being in that community of greatness. And that is hard for me to say that because I have the utmost respect for Kenny Easley. That group, those two (Chancellor and Thomas), they’re playing at that level."

I'm pretty sure he also said Ed Reed's the best safety ever.

So that's like 3 best ever safeties. You can do that sh!t when you're Ronnie Lott, though.