Halacha establishes specific protocols for situations where one has before him different kinds of bread that he will be eating, determining over which bread the Beracha of Ha’mosi should be recited. The first rule is that bread made from wheat is considered superior to bread from other grains, such as barley. Thus, if a person will be eating bread from wheat and bread from barley, he recites the Beracha over the bread made from wheat.
The second rule is that a large loaf takes precedence over a smaller one. On Friday night, for example, it might be more convenient to recite the Beracha over a roll and cut it up, rather than the large Halla, but Halacha requires reciting the Beracha over the larger loaf, assuming both are whole loaves. Of course, after reciting the Beracha and slicing the larger loaf, one may certainly proceed to slice and partake from the larger loaf. Similarly, if one has several different slices of bread, as often happens at restaurants, one recites the Beracha over the larger slice. Assuming that the slices are all of the same quality, which is usually the case, one recites the Beracha over the larger slice. (The Talmud speaks of situations where one has "Pat Nekiya" – bread made from fine flour – and "Pat Kiber" – bread made from coarse flour with the chaff. We do not generally have "Pat Kiber"; our whole wheat bread is higher quality than "Pat Kiber," and according to many Poskim, it is considered halachically superior even to white bread.)
It must be emphasized that this entire discussion applies only to situations where one will be eating the different breads in front of him. But if a person has several different loaves or slices and intends to eat only one of them, it goes without saying that he recites the Beracha on whichever he wishes to eat.
Another rule is that bread baked by Jews takes precedence over bread baked by gentiles. Halacha forbids eating bread baked by a non-Jew in his home, even if it is kosher, but one is allowed to eat bread baked and sold commercially by a gentile in a store or factory. The Sages enacted this provision to help prevent against excessive socialization with non-Jews, and therefore they forbade baked goods prepared by non-Jews in their homes, which could lead to close personal friendships, as opposed to baked products purchased in a commercial context, which does not generally lead to socialization. (It should be noted that for Shabbat, one should ensure to use only bread baked by Jews, and not bread baked by non-Jews, even in a store.) If a person has two loaves, one baked by a Jew and another baked by a non-Jew, and they are otherwise equivalent, the Beracha should be recited over the loaf baked by a Jew. If the loaf baked by a gentile is superior in quality, such as if the loaf baked by a Jew was made with coarse flour, then strictly speaking, one can recite the Beracha on whichever loaf he chooses, as each has an advantage over the other. Preferably, however, in such a case one should remove the bread made by a non-Jew from the table and recite the Beracha on the bread baked by a Jew, in order to avoid this question. This is the ruling of Hacham Ovadia Yosef.
Summary: If one will be eating different types of bread, and he must decide over which bread to recite the Beracha, several rules apply: bread made from wheat takes precedence over bread made from other grains, a larger loaf takes precedence over a smaller loaf (and a larger slice takes precedence over a smaller slice), and bread baked by a Jew takes precedence over bread baked by a non-Jew.
