How do you define "better"?
If you refer to the steel used both makers used harder steel compared to Italian makers incl. 2nd and 3rd gen Colts.
You are talking about handling? There are the shooters prefering the grip geometry of the Centaure which replicates the Colt 1860 Army (usually the ones with the mid to bigger size hands) over the ones of the Santa Barbara (usually the ones with the smaller hands).
You talk about pointability? Hands down the Centaure.
If you prefer a stronger, closed frame percussion revolver? Go for the Santa.
You wish to shoot longer shooting sessions without cleaning? The Centaure shines again.
There is one important difference to be considered, however: For the making of the Santa the historical measurements of the chambers' dia (.446") and rifling groove dia (.451") were replicated which has an impact on accuracy.
Regarding the latter, this is where the makers of the Centaure stepped away from the orginal. The Centaure was designed to be as accurate as possible. Hence, chamber dia and rifling groove dia are both the same (.446") like you find in a modern target revolver.
My 2 €-Cents.
Long Johns Wolf