My feeling is that real world examples, while more relevant, are more difficult to judge. Personally, I put a lot of weight in Bryan's ISO tests because in my experience they reflect lens sharpness better than measures I see on other sites. On the other hand, I don't put that much weight in them because most quality lenses are sharp enough for me anyhow, especially when stopped down.

For my money, the 24-105 is pretty sharp- geometry is a bigger issue than sharpness with this lens. The 16-35 is better in this regard at overlapping focal lengths, no question. A high quality prime will do better still.