You mean presidents who are not deep into the public consciousness nowadays?
If so I would go for William Henry Harrison (president in 1841 known maybe only for dying so soon after entering office), Chester Arthur (president from 1881 to 1885), Warren Harding (1921-1923).
Other possible candidates from my point of view would be Millard Fillmore 1850-1853, William Taft 1909-1913, and Calvin Coolidge 1923-1929.