I used the Summicron 50/2 which to me is excellent+
But I preferred the 35/2 which is more versatile, you can take portraits in situation, not really close ups (still, this is open to discussion). The aspherical version is extremely good and I think you could find one for ca. 1000$ if lucky (I got mine for 1200$ on ebay Germany where prices generally are higher than on the US market).
As for bodies, I would go for a Leica M if I were you. M4/M4-P or M6 if you prefer to have a built-in meter.
RF is great, I don't mean it's better than SLR (I use Nikon F3 too) but it is smaller and I attract less attention which is an advantage with street scenes (my #1 subject).