If sound quality isn't too much of a problem, I don't think that you can beat Sonys jog proof models... I have the DE-J825, and on setting 2 is (so far) totally unskippable, no matter how much knocking, or shaking you do to the unit...
One downside to that... There have been several reports on both here, and HeadWize, that the newer Sonys seem to have reliability problems (not so in my case though)