I don't know who the candidates for president will be this coming election, but I do know that a governor has a better chance than a senator. The fact of the matter is, a senator has to make tough, easily misrepresented decisions. Every 'aye' and 'nay' will be reviewed. If a senator tries to re-brand himself, he'll be cut apart by his own record, whether he deserves it or not.
A governor will also have his record reviewed, but it will be largely irrelevant. While a senator votes on things that directly relate to issues confronting a president, a governor only has to deal with state politics. He has effectively no record on military or international concerns. A governor can make himself anything on a national scale, since he is a null entity on those matters.
An exception might be someone like Hillary, since she's spent so little time in the senate that she may have avoided any real decisions.