A Manger deli on Charcas and Malabia used to have the best hummus I had ever had, but the last two times I bought it, it just wasn't the same... Not sure if that was a fluke or if they changed chefs. It is still pretty good but not as amazing as it used to be. It's a little pricier than some of the more traditional shawarma places, but when it's good it is worth it in every way. Tabouli used to be really good. Pretty much everything they have is excellent, especially their tartas.
Sarkis on Jufre and Thames also has excellent hummus, but not sure if you can get it take away there...
Good luck.