Travelon Backpack, Black

It's maybe not winning the most stylish award, but hear me out: she's very compact (perfect for crowded buses/trains), but holds SO. MUCH. STUFF. I've had many grocery cashiers be amazed how much I can load into this thing. It's great in the rain, is super durable, and the straps are actually supportive. The pockets are smartly placed and actually useful.

Years ago I lost this bag during travel and I literally re-bought the exact same bag. She's perfect.

Note: fits a small laptop but is often too narrow at the top for 15/17".