Saint-Saëns' classical, restrainted, elegant and very French style vs Franck's wagnerian, chromatic, intensely emotional and un-French (at the time) style.

Which do you prefer and why?

The premiere of César Franck’s Piano Quintet in F minor (1879) featured Saint-Saëns at the piano, to whom the work was originally dedicated.

At the end of the performance, Saint-Saëns abruptly left the stage, leaving the score behind—widely interpreted as a serious sign of his disdain.

Regarding Franck’s Prélude, Choral et Fugue, Saint-Saëns critiqued:
>Piece of a unsightly and inconvenient execution, where the Choral is not a choral, where the Fugue is not a fugue, because it loses courage as soon as its exposure is finished, and continues with endless digressions…

Franck rarely criticized; he was mild and kind by nature, but his students (like Vincent d’Indy) were sharper, seeing Saint-Saëns as superficial compared to Franck’s “serious” art.

Saint-Saëns was the most internationally famous French composer in 19th century, whereas Franck's influence was much deeper according to critics .