I have 3 Rhinowalk bags that are really good (saddle, top tube and handlebar bags), the finishing is flawless and it's really cost-efficient for what delivers. I've got some light showers with them and had no issues, never done tests with some heavier rain, though
there are good Rockbros models too, but it's a wide range of products and in my experience (personal and colleagues' comments) there are good and bad ones
I've used Sahoo in the past too, a saddle bag with the waterproof weld seam, but although the finishing was good the ziper gave up after like 6 months, and the store left me hanging on any comment about the issue...