I use a 511 Tactical All Hazards Nitro Backpack 12L. Looking at the pricing of some of the others bags posted, this one is not too bad with an MSRP of $129. 511 Tactical has sales where you can get it cheaper. Had several good sales over the Christmas Holiday.
https://www.511tactical.com/all-hazards-nitro-backpack.html
I carry my 15" MBP, 12.9" IPP 3rd Gen, a iPad Mini 4, chargers, adapters, hubs, mobile hotspot, sunglasses, and more.
I use this bag for my daily work bag. And have traveled with it multiple times. This backpack has 2 large chambers, 1 medium chamber, and 1 small chambers. The largest chamber has 2 pockets, put my MBP in one and IPP in the other and put some accessories in the middle between them. The second pocket is large enough to hold a couple days worth of clothes. It comes with 2 zippered velcro attached bags for holding toiletries, meds, etc. There are velcro tape straps attached to the inside the chamber to attach the detachable bags. Then the medium pocket carries keys, boarding pass, snacks, etc. Has small pockets for organizing. Even has pen slots to hold your Apple Pencil. The small pocket holds my sunglasses and also keep my Portable Battery and Lightening Cable for quick access to keep my iPhone powered up while on the go. This bag has a Conceal Carry Pocket too that is hidden. Just do not forget you have something in that pocket before you head to the airport.
The bag is covered, inside and out, with Molle Strap Attachment Straps. So can expand the bag with all kinds of attachments. And has Velcro areas for attaching badges, name tape, etc. I have some name tapes with my name. Got them for my Range bag. And got extras for my other bags, including this one. And have collected other funny patches over the years. Put some on this bag as well to give it some personality.
I have multiple 511 Tactical Bags. And have given them as gifts. They have all performed well. One of my favorites is the Rush MOAB Over Shoulder Sling Pack. Very nice for a daily bag when not needing large electronics. Holds my iPad Mini, wallet, phone, etc. And I keep a Rush 72 packed and ready to go as a SHTF Bag.