So, ive decided to get a messenger bag, because i run a lot of errands in the city and quick access trumps stability for me

features im looking for:
-volume between 20 and 28 liters
-padding on the strap
-additional stabilizing strap
-waterproof construction
-flap with 2 buckles, nol just velcro

pic related is the obvious choice, but what are the alternatives? What brands should I look into? Crumpler Dinky Di is already in consideratrion