Sometimes gluten-free baking can be as challenging and disappointing as Pooh's baking adventure. It's certainly a science, as no one single flour can successfully (at least in my experience) replace wheat flour. Add the need to replace butter and eggs and you really have a science experiment!
The gluten-free flours on the market include coconut, rice, corn, quinoa, flax, teff, amaranth, millet, buckwheat, arrowroot, sorghum, potato, tapioca, garfava, bean, oat, and montina. The flours I am most familiar with and use on a regular basis are rice (specifically brown rice), potato, tapioca, sorghum, oat, buckwheat, and coconut. I have listed below my two favorite flour blends, the ones I most often refer to in my recipes. The reason I don't use prepackaged flour blends is simply because I have never found one I like. While I do love Bob's Red Mill flours, their flour blends include bean flours which really give an off-putting taste, in my opinion. I'm happy to stick with their products that I like and do the messy work myself.
Here are the proportions for my favorite flour mixes:
Basic Gluten-Free Flour Blend
4 cups brown rice flour
1 1/3 cups potato starch (note that this is different than potato flour)
2/3 cup tapioca flour (which is also known as tapioca starch)
Multigrain Gluten-Free Flour Blend
1 1/2 cups brown rice flour
1 1/2 cups sorghum flour
1 cup tapioca starch
I have found the basic gluten-free flour blend to work best in cookies. The multigrain flour blend works really well in breads and cakes. I mix up large quantities of both and store them in ziplock freezer bags in my fridge. I typically use Bob's Red Mill flours, and I have found that amazon.com has the best deals, especially if you use their subscribe and save program.