There was a site that I read a year or two ago that had some pretty extensive info on Russell, specifically his business dealings and his relationship with his wife, which apparently ended in a bitter divorce. I thought it was the ad1914.com site (and it might be) but I can't find the articles about him.
He does strike me as a con man, who put up a respectable front but found every which way to make money, including by selling snake oil to Bible students. He does seem to have been a sincere person early in his life and ministry, but his ego got built up and at some point he got to like it too much, IMO. His religious ideas were occasionally pretty well out there (the stuff about the Pyramids of Giza stands out).
Rutherford, I think, wanted to leave his mark on the organization. At first, he seems to have followed Russell's lead, marking dates with supreme confidence and promoting world-changing events, but that caught up to him and I think he learned a lesson. After that, he decided to rebuild the organization from the ground up and made sweeping changes to doctrine and interpretation, essentially wiping a lot of Russell's work away.
I think that they both had the gift of communication, be it in their writings or their public speeches. They also understood the importance of keeping firm control of the organization and presenting a clear and united front to the public. This is what helped keep the organization together during tough times and grow it quickly during good times. Knorr seemed to learn fairly quickly that the age of big pronouncements was ending and the organization really just needed a steady hand. If there's one thing he could have changed, I bet he would have told Franz to drop any talk of 6,000 years since man's creation and anything to do with 1975.