Both look pretty horrible today but, in general, N64 just felt more solid while PS1 games often felt flimsy.
Music, details, cutscenes, all go to PS1 (I never played Saturn). PS1 even had more content 99% of the time. Hell, games like Gex2 even had better draw distances over their foggy counterparts. To me, N64 games just had "weight" to them.