On Monday, the Pew Research Center released a survey looking at how Americans see these dueling problems. To do so, though, it used an interesting strategy, asking respondents how big fraud or suppression would be depending on how many incidents occurred (in a million-voter election).
Overall, voter suppression was considered a major problem by more Americans. In each case, the number of people saying that fraud or suppression were a problem increased as the number of theoretical incidents increased. Put another way: More voter fraud or more voter suppression is seen as a bigger problem.