Check out how the 19" handles with the longer stem versus the 21" with the stock stem. Generally they design 'em to handle best with the stock length stem. The other issue with the 19" is that you generally want to avoid using saddle relocation as a means of changing bike fit to avoid potential issues with your pedal stroke (and knee pain, etc.). I would recommend the 21" for you; that's what I've been fitting people your size on at our shops and no complaints yet.