Another vote for Ortlieb.

I'm a pretty aggressive rider as well, lots of sprinting and holding or pushing my way into lanes when I need to, and the set of Ortlieb Front Roller Pluses I experimented with a for a month or so on the rear rack on my Giant OCR never came off and never felt even slightly loose. Rock solid.

I ended up not liking panniers for other reasons, but when I get my touring bike (any day now) I plan on going Ortlieb.