I really like my Ortlieb, with a few caveats:
Map holder flaps over 20 mph air speed.
Really needs one mount per bike it'll be used on.
Interferes with bar-mounted headlight.
Other than that, it's spacious, holds a decent load well, mount is secure, gives you room to put your fingers between bag and bar, is waterproof, and you can keep a camera in the side pocket.