The backpack has been popular for quite sometimes now, and I personally have got one myself. It looks good because it knows how to be simple.
The one I have is a medium size. It only has 2 compartments: big one for the books and small one for miscellaneous. While this sounds underwhelming, this is what I need and what most people need. The design of the one I have is also not jarring. It boasts a plain color, but a very comfortable pair of straps.
I use this backpack for a while now, and it matches everything I wear. I honestly believe that it will be very difficult for me to get bored of this backpack.