fwiw, I find store-bought salad dressings hard to portion-control. I used Walden Farms dressings, bought inexpensively from iherb.com or Vitacost.com. I think their Ranch got good reviews, though my faves are italian vinaigrette, Balsamic, Sesame Ginger. I did low carb--~25 net, and every little carb adds up. If you are going for a higher limit, the little bit in the dressing isn't so critical as long as you are okay with portion size.
You might be surprised (as I was) at how easy it can be to make yummy no-carb salad dressing. If you are used to store bought, it may take some getting used to. There are so many delicious kinds of vinegar & oil. If you have never had good, cold-pressed, virgin olive oil, give it a try!