Apparently this is indeed a direct quote from Ramsay:
"this author should be placed along with the very greatest of historians.”
Ramsay, William. The Bearing of Recent Discovery on the Trustworthiness of the New Testament. Grand Rapids: Baker, 1953. p. 222.
In light of this information I make the following correction:
Well, it seems that the phrase "world's greatest historian" was not pretty much what Ramsay actually said. However Additionally, there are still those, such as DOC, that do agree with Ramsay and also regard the author of "Luke" as a great historian.
There, now that it's been corrected, I can continue:
I recognize the historical value of any ancient text, I just have (potential) issue with referring to the gospel authors as historians (using the modern usage of the word) much like I have issue with referring to the gospels as eyewitness accounts.