May I suggest Manhattan Portage? I've recently purchased their straphanger bag for commuting to and from my college campus which is about 5 miles or so, I can carry (3) half inch binders, my 13inch laptop, my ulock, my ti-84, and a good assortment of pens and pencils which i rarely use except for 2 of them. I was in the situation of looking at bags and preffered the style that Manhattan Portage had which was low key and pretty basic which fits my style. its comfortable for me and it also has a stabilizer strap to prevent it from sliding to the front while I bike.

Plus they're pretty affordable too

I can try to post pictures tomorrow in between classes if anyones curious as to the size of the bag, it's not too big from the outside, but it holds quite a bit and at times im surprised by its capacity.