It can be really confusing choosing the right focal length for street photography. There is a general rule that 35mm is the conventional focal length one should choose. My personal thought is that there is no rigid rule that everyone must abide by. Each person has their own preferences, and most importantly, they have their own eye and style - when it comes to seeing and capturing moments.
I'd love to share some of my own personal experiences - of when I first started out. Like most people, I started street photography with 35mm. However, I felt uncomfortable being too close to strangers and as a result, I found myself cropping lots of my images. As a result, I decided to try shooting at 85mm or 135mm. I felt much more comfortable keeping some distance from the subjects, and I was able to focus more on what I was seeing. In my opinion, using telephoto lenses can create powerful and moving images (particularly portraits). I grew to really love using my 85mm and 135mm lenses. If you're just starting out street photography, or have been struggling with wider focal lengths, I really encourage you to experiment with long-focus length. You might grow to love it like I did! As time went on, I was eventually bold enough to take images at 35mm - though I still love using my 85mm.
Here are some examples of my street images taken at 85mm:
Use and experiment different focal lengths, and discover what you're comfortable with, and what is most compatible with your style and what you're trying to capture and communicate through your images. There's no one rule!
What lens do you like or have tried? What do you like? Let me know! :)