I suspect the answer to the title question is “all of them.” Many of those who came in second, third, or fourth to Armstrong have already been connected to of doping, and most of them have already confessed or been convicted. I don’t think it follows, however, that the outcome would have been the same had no one been doping. Different bodies will not necessarily react the same way to the drugs, and different people may be able to make more use of the drugs than others. So maybe the results would have been the same, but maybe not.