Bread flour is crucial for making bread. Gluten content is most important. Buy the bread flour in bulk if available.
I was making bread myself for three years now. I used several books and tried several recipes. Now I make two types of bread: "everyday" and challah. Everyday bread consists only (or mainly) of the wheat flour, water, yeast and salt. Bread flour is no superstition. As every flour package tells us, wheat is different from other grains because it contains gluten -- special fibrous protein that dissolves in water and, with starch, forms films that capture gas produced by yeast and make the bread rise. Bread flour has higher gluten content (up to 14%, while all-purpose or pastry flour has 7-10%), so do use bread flour for bread. I use organic flour if I can, because I believe it tastes better; also, it seems a good idea to use stone-milled and not steel-cut flour, because in steel-cutting process flour gets hot and part of the gluten denatures.
I used to get bread flour from the small local store that sells bulk grocery, Buy the Pound, in Ann Arbor. That store carried organic white unbleached bread flour from the local mill. Now that I moved and haven't yet found a similar local store here in Contra Costa, I buy prepackaged King Arthur's unbleached white bread flour. It's not organic and not as fresh (I'll explain it later), but it is high in gluten and therefore has great mechanical quality. The long fermentation in my recipe partly makes up for the flavor loss.
Flour is made of grain. Grain has an outer shell, a germ, and a starchy part called endosperm. Outer shell doesn't grind into powder, it turns into flakes that can be sifted from the flour. Germ contains oils and proteins other than gluten. This part of flour gets rancid quickly. If you buy bulk flour, you can smell and taste for yourself if it's fresh and appetizing or stale and dusty; bulk grocers usually get their produce from local producers in small quantity. Prepackaged flour has no perishable (and flavorful) parts left. But, as I mentioned above, long fermentation creates flavor, too. In my experience, King Arthur's flour is superior to other supermarket brands. Another popular brand is Arrowhead Mills; for some reason they sell bread flour in ridiculous one-pound packages. King Arthur's makes organic bread flour as well but sells it only by the 50-pound sack.
I prefer white bread to whole wheat because, in my experience, whole wheat flour make bread coarse, wet and dense. Whole wheat bread contains small film-like pieces of bran, which is considered healthy. I read that pieces of film trap the air and makes bread lighter, but never seen that happen. 20% flour -- 4/5 white flour to 1/4 whole wheat -- makes flavorful, rich bread with thick crust, but not as springy, fibrous texture as white-flour bread. We eat bread with food or in sandwiches anyway -- I can add vitamins and flavors later.
Rye has strong characteristic flavor but no gluten. I made rye bread with 1/3 of rye flour. It was wet and dense, but in a good, fitting the taste way. Buckwheat has no gluten, either, but interesting nutty flavor. Unfortunately, my family doesn't like it, but I do.
Semolina is a coarse yellow wheat flour used to make pasta. It makes great bread crust, too: use it to dust the board before final kneading and shaping of the loaf.
See also: kitchen, homemade bread, challah, chicken soup, knedle, Ann Arbor.