Well Hell, if we're going to open this up to all the DBs to ever play for us...
Biggest hitter was the Eraser Reggie Nelson. Best free safety to ever wear the Orange and Blue (and yes, I know all about Louis Oliver).
Nelson was key to that 2006 National Championship team in that because of his range he was basically able to play both safety spots himself and allow Tony Joiner to play as a 4th linebacker. We used to make the joke that 2/3 of the Earth's surface was covered by water, the rest was covered by Reggie Nelson. Nelson was a ferocious hitter because of his timing. He wasn't as big as Louis Oliver but his timing was just uncanny. Early in games, he would bait a QB. He would play off the receiver, look disinterested, then burst into his break the instant the QB made up his mind to throw to the "open" receiver. Nelson arrived the same time as the ball and either intercepted it, or delivered a crushing blow resulting in an incompletion or fumble (and alligator arms for that receiver for the rest of the game). On my all-time UF defensive team, Reggie Nelson is the starting Free Safety and Louis Oliver is moved to Strong Safety. And I'm a big Louis Oliver fan. Nelson got robbed of the Thorpe Award following that '06 season. Absolutely robbed. I don't think he gets enough credit from Gator fans because of his short career but he was the best FS we ever had.
I want to give a shout out to Ahmad Black as the best tackler. Major Wright was the big hitter and Black was a smaller dude. We all assumed Black should play FS and Wright SS. Coaches were right and we were wrong. Ahmad Black was the best form tackler I've ever seen. Perfect. Every time. Wanna teach proper tackling technique? Show video of Ahmad Black. That dude got every ounce out of his talent. Loved him. He tackled dudes a lot bigger and a lot faster than him and he did it over and over again. Coach's dream, always in the right position, always the right form.
On the other side of the coin, Kyle Jackson was a physical specimen. Great speed, looked great running out of the tunnel, never took the right angle in his life. Dude was the king of bad angles. He'd be right there, in perfect position to make a tackle, and he'd take a bad angle on the ball carrier and it was 6 for the bad guys. Over and over and over again. Wondy Pierre-Louis was another physical specimen. Ran like a gazelle. Amazingly gifted athlete. But he didn't know how to play CB. Neither did Joe Haden (another gifted athlete) in 2007. I remember them running stride for stride with the receivers in perfect position. No ball awareness. It's like they thought it was a footrace or something. The ball would come in and they wouldn't make any play on it. Receiver sticks out his arms and catches it with no opposition. Whereas Haden learned how to play CB and became an elite CB, poor Wondy never figured it out. He was a solid contributor on special teams though.
Some other names you may want to consider (since we're expanding) include Jarvis Williams (a corner for us, a safety in the NFL with the Dolphins), Fred Weary, Lito Sheppard, Janoris Jenkins, and VHIII.
Alex.