I get cards and letters from all over the world. Every Thursday, one of my interns dumps a heavy canvas sack of it on my desk. After I've burned the ones that call me rude names (the letters, not the interns*), if there are any left, I try to answer them. Like this one, from Dev in South Africa:
"What can be used in place of all-purpose flour? I live in South Africa and here we normally get cake flour and bread flour, and sometimes self-rising flour, but not all-purpose flour, though many recipes call for it. What should I do for a substitution?"
Different kinds of flour exist for different purposes. For crusty breads and pizza, you want a strong flour with a high gluten content. For soft, tender cakes and pastries, cake flour, which is lower in gluten, is the way to go. For making pasta, you want even harder flour.
Note that in some cases, as with durum, which is used for making pasta, it is a different strain of wheat altogether. Hard wheat and soft wheat are generally the same strain, but are planted and harvested in different seasons. So-called winter wheat is harder, and used for bread flour. Spring wheat is softer and is used for cake flour.
Now, all-purpose flour is a blend of hard and soft. The idea is that it's hard enough to use for making bread but soft enough to use for making cakes. It's not the ideal flour for either one, but at least you don't have to keep multiple bags of flour in your pantry (like I do).
So to answer your literal question, to substitute for all-purpose flour, you'd combine about 70 grams of bread flour with about 60 grams of cake flour.
That will produce the middle-of-the-road compromise of all-purpose flour.
Fortunately, you don't have to do that! But the real answer to your question is, it depends on what you're making. Given the available choices you described, So if you're making bread, hard rolls, pizza dough or other tough, crusty products (and also pasta) use bread flour.
But don't simply substitute a cup for a cup. This brings us to one of the important issues in the world of baking. Professional bakers don't measure flour in cups — that's way too imprecise, and leaves room for all kinds of errors depending on whether the flour is scooped out, spooned out, sifted, unsifted, and so on. The only way of ensuring a recipe's accuracy is to measure the flour by weight.
And crucially, bread flour and cake flour have different weights. So measuring by cup means you could wind up using too much or too little flour.
Fortunately, one of the universal culinary constants is that a cup of flour is 130 grams. So for however many cups of flour your recipe calls for, use 130 grams of flour. It doesn't matter whether it's cake, bread or all-purpose. 130 grams is 130 grams.
Of course, if the recipe is already given in grams, use however many grams it says.
*But don't give me any ideas.