I find that SWFD is more accurate at the time of publication. The organization of the data is excellent, and there is much more useful background information that is easily accessible without a computer. But its nature of being a "static" database can gradually make it become outdated, especially in the (relatively) fast moving evolution of public safety radio. I use it primarily for background information.
I find that RR is generally accurate, and the fact that it is an interactive database makes it less likely to be outdated. However, I feel that the open access submission process can make it unreliable at times. Although the page managers exercise good judgment, the anonymous nature of contributors can make some data inaccurate and very frustrating for users who rely on it as "gospel" truth.
I do not want to start a flaming contest either, and I only speak from my own experience: I have found that well researched hardcopy database can be the most accurate, but only for the moment. I find RR can have the most rapid updates, but you have to take the data with that proverbial "grain of salt."