50L Panniers Bike Bags, Waterproof Bike Panniers Made of High-Density 600D Polyester for Durable Use, Bike Saddle Bag come with Reflective Trim and Rain Cover, Easy Organize in 7 inch Rack

I use panniers on both sides. I used to use this $46 double pannier which worked fine, but I disliked how much of a pain it was to mount, unmount, and carry off bike - I'd probably still be using it if I wanted to keep it on a bike full-time. I now have a pair of these $40 roll top waterproof panniers which are much nicer for taking off the bike.