When I used to live in Chicago I was using my bike a lot for those clients of mine who lived in the city. Depending the amount of weight and the type of equipment that you carry I would suggest a ruck instead the pannier rack. The center of gravity was not ideal for avoiding cars and pedestrians. For that reason I switched to a rucksack which made my trips much easier and more fun (I was getting a workout as well). After many years of searching I have decided that the GORUCK backpack is the best one. It can hold up to 100 lbs of weight (as long as your back can handle it as well) and it didn’t kill my shoulders or my back. Here is the website in case you would like to take a look at:
They are not cheap, but they will last for ever!
I hope this helps.