If you'd asked me this question three or four months ago I would have voted for the 50 without a moment's hesitation. The 50 is the lens that I learned on and, up until very recently, I was quite sure that I saw the world photographically through 50mm framelines. However, recently, I find that I am using the 50 less. I still use it often. But more and more I am reaching for my 35 and loving the results it is giving me. And now that I have a 21, don't even get me started!