I've been a rangefinder man for years now, first in medium format, but now 35mm since I just got my new Leica M6 today! I think SLR's are ok in 35mm, but for medium format get too bulky, heavy and just awkward to use. Rangefinders are small, easy to handhold and quick to use, and best of all, the optics are sharper than SLR optics.