Clinton won against all three Republican candidates; 45 to 37 percent against Christie, 50 to 34 percent against Rubio and 50 to 38 percent against Ryan.
"Former Secretary of State Hillary Clinton would start a 2016 presidential campaign with enormous advantages," said Peter A. Brown, assistant director of the Quinnipiac University Polling Institute. "She obviously is by far the best known and her more than 20 years in the public spotlight allows her to create a very favorable impression on the American people. But it is worth noting that she had very good poll numbers in 2006 looking toward the 2008 election, before she faced a relative unknown in Barack Obama."
Christie beat Biden 43 to 40 percent, as well as Cuomo, 45 to 28 percent.
Cuomo was also beaten by Ryan, 42 to 37 percent, while he tied with Rubio, 37 - 37 percent.
Biden, meanwhile, led Rubio 45 to 38 percent and beat Ryan 45 to 42 percent.
"Although some Republicans don't think New Jersey Gov. Christopher Christie is conservative enough for their taste, he runs best of the three Republicans tested and would defeat two of the top Democrats," Brown said. "He obviously is doing better than the Democrats' rising star, New York Gov. Andrew Cuomo, despite other indications of anti-Republican sentiment."
Quinnipiac University questioned 1,944 registered voters between February 27 and March 4. The poll has a margin of error of plus or minis 2.2 percentage points.