Personally, i'll take Roy over any other safety in the league. Don't even talk about Ed Reed, because he's on a defense with a ton of superstars and he's always had a good free safety playing beside him. As for Polamalu, let's see what Roy is doing in 5 years after his D-Line and Linebackers and D-Coordinator have perfected the 3-4. Roy is an absolute beast. Of course he's a liability in coverage, or maybe not since he has a pick in each of the first two games of the season.
Sean Taylor of course is great in coverage, besides that he got beat on 2 touchdowns last night. And don't tell me it wasn't his fault on the Glenn TD, because everyone blames Roy for the 2 Moss TDs last year and it's the same situation with the corner hanging the safety out.