SwissGear Valve for the past 3 1/2 years. Got it for $30 from a Newegg Flash deal. It's held up surprisingly well and it fits everything I need without being ridiculously bulky: 15" MBP, ATH-M40x in hard shell case, iPad, stylus, spiral notebook, dot grid notebook, tiny travel router, battery charger, extra AA batteries, and my external trackpad + keyboard when I need them.

https://www.amazon.com/SwissGear-Valve-Tablet-Backpack-Lapto...