for me its all about the look and feel of the putter. the look has to not only fit my eye, but it has inspire confidence (a SC futura putter for example, doesnt in my opinion). as i prefer a more traditional/minimalist look to my clubs (obvious based on the clubs i use in my signature...), many of the classic SC and ping putters are usually to my liking.
beyond the look, the feel is the ultimate piece that has to be there. the key there is that the feel is always going to be a personal deal. while i like the looks of the new ping putter's (started playing years ago with anser's), and their attempt at making a higher end line, the feel and sound they produce isnt as much to my liking as the SC circa 62 putters.
while the SC brand and the extensive marketing they have done obviously comes into play on some level, i ultimately agree with the bolded part of the above quote... if you can consistently make putts with it, then its worth every cent... even if its just all in your head