I don't see it. I can't think of any amazing match that Taker has had that really blows Cena away.
Cena was pretty bad for a while, but got better around 2004-2005. I think working with Angle a lot helped him.
Some of Taker's late 90's stuff is pretty damn awesome. Plus I'm a blind mark for his dive over the top rope he busts out everyonce and awhile. Taker's best is better than Cena's best at this point, but he also has lower lows, and a larger selection of matches to pull from.
I'd say Taker/Foley Hell in the Cell is beyond anything Cena's really done at this point, but Cena will more likely than not have an iconic match like that in his career.