I'm not one for buying salad dressings If I'm serving a leafy salad with something some oil and acid will do just fine. Oliver oil, vinegar like sherry, cider, or even lemon juice, a smashed clove of garlic to flavour the oil, S+P and a herb depending on what I'm using it for - oregano, tarrgon etc. I don't like creamy dressings, they just drown the veg/leaves. If it's not a leafy salad - lentils, rice, cooked cold vegetables whatever, then things'll get a bit more interesting.