You should use the lens you think works best for whatever situation you happen to be in. There is no reason to decide what lens to use based on predetermined absolutes. All focal lengths from 17mm to 300mm have provided me with what I would call successful street photos. The lenses I use most for street photography are the same lenses I use most for any photography: 28, 35, 50, 135, and 24 and 200 every now and then. Occasionally 17 or 300 in the past, though I have now sold or traded both of these lenses. I would say that I use the 28, 35, and 50 equally most. I usually use the 35 instead of the 28 and 50. I use the 135 about half as much as either of these shorter lengths. I will use the 200 mostly only if I also have a 28 or 50 on another camera ready to shoot. I generally will have 35/135 or 28/50 on two cameras.

100mm on 6x9 has a wider angle of view than a 50mm lens on 24x36mm format. It is almost identical to the AOV of a 40mm lens on the smaller format, so is actually closer to a 35mm-focal-length-like AOV than to a 50mm-focal-length-like AOV. A 127mm lens on 6x9 will be closest to a 50mm lens on small format. A 65 on 6x9 is a little wider than a 28 on small format.