There's not just a difference between bleached and unbleached, but also between flours of different regions. I use a Southern bleached all-purpose flour for biscuits, pancakes, and muffins; basically anything that's leavened with baking powder. I use unbleached and bread flours which have a much higher gluten content for making breads and pizza crust.
Some southern bleached flours are white lily and martha white. Northern all-purpose flours will have a higher gluten content. I know King Arthur is one. Then there are some nationwide flours which fall in between, such as Gold Medallion and Pillsbury.
The main reason to use bleached or unbleached is gluten content. If you don't want to take my word for it, make biscuits with unbleached and make them with bleached, given both are all-purpose. The lower gluten content flour makes for biscuits that are more dense and moist.