Barber made the comments Wednesday on his CBS Sports Radio show, saying he believes that Eli Manning's ability to win when it counts trumps Peyton's statistical accomplishments.
"The expectation was that he was never going to be Peyton. I remember having these conversations with people who watched Eli in college, saying, 'He's good, but he's never going to be Peyton, he's not Peyton.' Guess what? I think he's better than Peyton.
"Because of clutch. What matters in sports? It's winning and losing. You get to the stage and what do you do? Eli's gotten there, and he's won," Barber said.
Eli Manning, 32, has led the Giants to two Super Bowl titles and is 8-3 in the postseason, while Peyton, 37, has one championship and has a 9-11 playoff record.
Following his retirement in 2006, Barber questioned Eli Manning's leadership skills. Now, however, he thinks his former teammate can be one of the top five quarterbacks in history.
"For Eli to crack the top five of all time, he's got to have a 2011 season a couple more times and win another Super Bowl and be Super Bowl MVP, and then I think he's in the discussion for the top five of all time," Barber said.
In the Giants' 2011 championship season, Manning threw for a career-best 4,933 yards with 29 touchdowns and just 16 interceptions.
Peyton Manning's career high in passing yards came in 2010, when he threw for 4,700 yards. He, however, is the NFL's active passing leader with 59,487 yards and ranks third on the all-time list. He also leads all active quarterbacks in touchdown passes with 436, which is second all time. Eli Manning's 211 career touchdown passes have him fourth on the active list and 26th all time.