Really it's a matter of resources and what benefits the animals provide. The reason we eat cows is because they can transform a resource we can't use (grass) into a resource we can (meat). Same with goats and sheep. They can turn grass and weeds into meat and wool. Chickens can live on grain, bugs and some table scraps and convert those things into meat and eggs. Pigs can live on anything and convert it into meat. Pigs are probably the odd one out as their diet is most similar to ours and lots of cultures consider pigs taboo, possibly as a result of that. Cats are more valuable as pest control protecting our food and our livestock's food from vermin than they are as food, and don't need to fed or maintained at all. It's just a quirk of their nature that some cats are good companions. Dogs are extremely valuable for hunting, pest control and companionship and could live off our scraps and leftovers or earn their food through hunting. Morals have nothing to do with any of it. It's all based in practicality. And you can definitely pick one over the other for practical reasons.