Hi Bran,
welcome to the forum from Holland! Make sure you post some shots, no matter what Leica you get? :angel:
I'd say get an M2 or an M4/M4-2/M4P, they are fairly easy to service, have excellent track records, will not have a flaring rangefinder patch (which quite a lot of M6's did have) and framelines are not too intrusive in the viewfinder.
For street photography I recommend a 35mm lens as your first lens, for the angle of view and the increased depth of field it gets you: it's easier to focus and there's more street life in the photos! The Voigtländer Ultron 1.7/35mm is a nice lens if you can find it, but the Color-Skopar 2.5/35mm is very good too. For older, lower-contrast lenses, turn to a Canon 2.8 or 3.2 or 3.5/35mm LTM lens, which you can easily mount using an LTM <-> M adapter, made by Leitz.
Good luck finding your first Leica, and happy shooting!