Why do either? Make your own!
First off, store-bought salad dressings are usually loaded with MSG's, preservatives, food dyes and other toxins, not to mention bad fats and sugars. Your best bet for healthy is homemade dressings.
There are so many different recipes for making a healthy salad dressing so that you can skip the boring plain and the unhealthy store-bought dressings. For instance, I like to make raw food dressings using EV olive oil, avocado oil, walnut oil or any other wholesome cold-pressed (expeller-pressed), organic oil that is high in Omegas. I buy an organic jar of mixed spices to add flavor. You should also watch out for GMO (sourced from genetically modified foods) oils like peanut, canola, safflower, etc. Then, add in some cider vinegar -- I used Bragg's apple cider vinegar with the "mother".
But, let's face it, spiced up vinegar and oil gets boring, too. You can Google some homemade dressings that are used for a raw food diet, as an example. I've tried a few and they were actually delectable. For instance, take half of an avocado, juice an orange or 2 and blend them together with some spices. You can get a handful of recipes from http://www.living-foods.com/recipes/ that has a variety of dressings like a pine nut basil dressing (which, I've tried but added a little bit of spices), pineapple chutney, mango salsa, etc.