The N64's games honestly aged better. A lot of the PSX's games suffer from problems. When it came to early 3D, compare both the art and controls of Super Mario 64 with those of Tenchu. I loved Tenchu when it was originally out. I now find it almost unplayable. The realistic 3D of most of Sony's games also didn't age as well as the stylized 3D of Nintendo's titles.
I had some great experiences on the PSX, and it may have done a lot to revolutionize the market, but it doesn't stand the test of time as well as the N64.