Thanks. Oddly enough, the Giant Revolt Advanced 0 doesn't have top tube bag mounts. It's got every other mount under the sun, but not those. Straps it is. I went with the 480.
I have a small Velcro mounted Specialized one. Magnet holders so it opens closes easy. Good capacity without being an issue for knee bumps. They don't make it anymore but a retailer may have some left or ebay.