I LOVE bleu cheese dressing. I always have, and in fact, was 8 years old before I knew that there was a whole shelf at the commissary of different salad dressings! There are several that I've come to like on some level over the years, but my favorite creamy dressing will always be bleu cheese. My earliest memories of salad dressing were Kraft's Roka Blue Cheese, which my father called Roquefort, instead of Blue Cheese. I learned later that not all bleu cheese is Roquefort, as only cheese produced in the Roquefort region of France is actually called that. As I understand it, it's rather expensive as well.
I've tried virtually all of the brands available at the major grocery stores in the Tarrant County area, I think. As far as store-bought, in a bottle or jar, Litehouse (Walmart) and Marie's are my go-to quick & easy to get choices. *don't bother with the "low fat" versions of commercially prepared ones, they just don't have the rich flavor. Central Market has a wonderful version in their bulk refrigerated bar, though I doctor it a bit to add a little more black pepper, and more crumbled cheese.
My absolute favorite though, is the homemade version that I make:
1 pkg softened cream cheese (I've also used reduced fat or neufchatel cheese to reduce some of the fat)
6 oz buttermilk
Garlic powder ~1/2tsp
Basil flakes ~ 1/2-3/4tsp
Black pepper ~ 1/2 tsp
8oz blue cheese crumbles
Mix the softened cream cheese to and buttermilk on low speed in deep bowl (a shallow bowl will splatter EVERYWHERE, trust me on this), adding seasonings to blend well, then add blue cheese crumbles until all mixed in. Makes about 2 & 1/2 cups of dip.
This recipe makes more of a dip than a dressing, which is my preference, however if you want actual dressing consistency, add more buttermilk a quarter of a cup at a time until you achieve your desired consistency. This will also mellow your blue cheese flavor out some as well, so if I am making actual dressing, instead of dip, I add more buttermilk and more blue cheese crumbles because I so love the rich tang of the cheese.