So, a couple of points between the 24mm vs 28mm, a tough choice as they are so similar.
1. Both are fantastic. However, the 28mm is a bit sharper.
2. The 28mm is also shorter and thus slightly more compact, as it has 1 less lens element.
3. The 28mm is about $50 cheaper.
4. For APS-C use, either the 24mm or 28mm are great for street photography. The 24mm will give you a "wide normal" FOV, while the 28mm will give you a "normal" FOV. It is 100% personal preference whether you want wide-normal or normal. Personally I think 28mm is the perfect focal length for street photography on APS-C.
5. For full frame use, arguably the 24mm is more desirable as it can produce more impressive looking landscapes with the sweeping "24mm look." 28mm is a bit of a compromise focal length between 24mm and 35mm on full frame IMO.
6. Otherwise, both are great for street photography on an APS-C camera - the 24mm will give you a bit extra width, while the 28mm will be a bit sharper and less prone to perspective distortion on the edges than the 24mm.
If you plan to buy a full frame camera in the future, I'd get the 24mm - as it will serve well for street photography on APS-C, but will double duty as a landscape lens on a full frame camera.
If you don't plan to go full frame anytime in the near future, I'd get the 28mm - as on APS-C 28mm is a bit sharper, more compact, cheaper, has less perspective distortion at the edges, and on APS-C gives a bit more ideal focal length for street photography IMO.