A TLR with a WLF, any rangefinder like the canonet QL17 GIII or try an Exakta with a WLF. I use all of these and have been successful at getting great candid street shots because most of the time people don't even notice when I am looking down into a WLF. They probably don't even recognize them as cameras. Most rangefinders are very quiet and unobtrusive enough that you can take a shot and people don't even realize it. Anytime people have confronted me about taking pictures of them, I tell them that I am taking random shots of the area and that they just happened to ruin my shot by walking into the frame.