I love luggage, and my favorite piece I’ve ever bought is a big carry-on backpack by the Japanese company Master-Piece. Along with a whole bunch of other stuff, it’s on half-off sale at Mr. Porter. (It’s the mustard yellow one above, though mine’s red.) I love it so much I bought a day pack in navy blue (also pictured above) just now. It’s beautifully made, beautiful to look at, just the Platonic ideal of “nylon backpack” as far as I’m concerned. Expensive even at half-off, but seriously awesome.
There are several designs on sale right now. You can find the rest of the sale (tons of great clothes, too) right here.