Saturn was superior to both, in the past I thougth they're equal but reconsidered.
Virtua Fighter > Tekken > 2 or 3 horrible N64 3D fighting games
NiGHTS > >Mario 64 >>>> Crap Bandipoop
X-Men vs Street Fighter and every other 2D Capcom arcade perfect port >>>> horrible PSX ports >>>>> N64 non-existent ports
Sega Really >>>> Ridge Racer
UMK3 was also a Saturn exclusive.
And I don't even mentioned lots of obscure Japan imports, many of multiplats PSX games are also available on Saturn with similar or better quality, PSX is superior only if you put emphasis on JRPGs and shovelware trash like sport games that were being released years after console's death (FIFA 2005, lulz).
BTW there was a great commercial done by Polish Saturn distributor back in the day (Lanser) which nailed both PSX and N64 flaws: