High-quality backpacks are a combo of functionality and style. If you're buying a backpack for everyday use, we highly recommend focusing on models that both have enough storage space for your needs and either complement or blend your personal everyday style. If you're unsure about the color and style, black and brown backpacks go with pretty much everything.
A good everyday backpack should also be durable as well as offer some waterproofing if you live in a particularly rainy area.