I would recommend an M5. Best meter ever in a Leica. You can change shutter speeds on the fly without taking your eye off the viewfinder. Quieter than an M3 ( have both so can speak from experience). Better build quality than later Leica's. Again I can speak from experience. Way easier to load than an M3 which is a pain in the arse if you are street shooting.

Personally I prefer my 35mm lens but still love the 50mm Summicron when I need it.