I had a PlayStation at the time and it made crash instantly look old and dated. 3d analog full range of motion. huge diversity of worlds. way better soundtrack. no load times. everything felt giant and open and begged you to explore. great controls. great soundtrack.
crash felt boxed in, felt like you were swimming through shimmering pixels. it felt archaic. the camera was trash, with weird angles not showing properly due to psx limitations and varied angles of ground. you're controlling a character in 3d space with digital controls for crying out loud.
Mario 64 opened everything up and led to non-stop imitation and inspiration. Crash was forgotten. ultimately as "pretty" as Crash was, poor gameplay doomed it. meanwhile merely controlling Mario in Mario 64 was so fun that little were overjoyed to run around the courtyard for hours.
claiming Mario is "clunky" while crash is smooth is a straight up bizarro land claim.
I think sterling nailed it here:
http://www.destructoid.com/ten-classic-games-that-did-not-age-well-154409.phtml