Shawarma
Shawarma is the standard fuel for a Waterloo student. If you aren't eating shawarma, you aren't Waterlooing right.
Shawarma Hub
Shawarma Hub in the SLC Food Court is likely the worst food on campus. That said, for this reason, it never has a line, even at peak lunch hours. If you're willing to take the food poisoning gamble, you could eat here.
Shawerma Plus
Shawerma Plus in the University Plaza is the objectively best shawarma considering the price/portion/distance/ratio. It's a short walk from CPH and easily worth it.
Lazeez
Overrated and will give you stomach problems. Not worth it.
Osmow's
See the Lazeez section.