Depends what light you're going to be shooting in, and what effects you want.
A general purpose 200 - 400 speed C41 will give good results for most subjects. Fuji do plenty of variants.
If you want a more muted pastel effect, Portra NC will give a very natural, effect (Quite different if you compare it to a lot of consumer film which looks quite gaudy in comparison- I like it a lot) but is rated at 160 iso
If you want a very saturated, yet reasonably well controlled film Ektar will be one to try, but its also quite slow at 100 iso.
Remember also that quite a lot of street photography is done with B&W. Can add a degree of hard edged realism to the work if needed, especially if you use good old tri-x or some of the traditional ilford emulsions and process them with Rodinal.
If you want to stick with just C41 processing, but want B&W XP2 super can work well, and is ultra flexible as regards exposure (rate it anywhere between 200 - 800 easily, up to 1600 at a push)
E6 slide can also work well, but needs really good attention to exposure. If you get time to set up your shots, its worth considering. If you are doing fast shots in a journalist style, might not be the best bet