According to the Huddle Report, Bob McGinn from the Milwaukee Journal Sentinel has been the best draft prognosticator over the last few years. Now that Rick Gosselin does not do mocks anymore, I'll be paying attention to Bob McGinn a lot more. Here's a good article on the "bigger, stronger, faster" philosophy and which teams favor that. I hope Whaley, Marrone and company continue to build the Bills on the philosophy Nix introduced.
BTW, the Huddle Report has a great page on ranking the mocksters over time.