I'm currently enamoured with my Canon VI-L so I'm going to recommend that.
Fastest rangefinder I've used so far, so a good choice for street. The viewfinder is parallax corrected and 1/1 scale so you can frame with both eyes open. I've got a really smooth Jupiter 8 attached that I can focus with one finger, making the whole thing a one-handed operation if needs be. Finder can switch to 35mm view if you want a more standard street FOV.
Both Barnack and Contax finders are likely a bit too pokey for quick street photos if you ask me. Not forgetting how heavy Contax are too...