Most impressive 3D graphics on 5th gen consoles

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While they may look crude today, the 3D capabilities of 5th gen consoles like N64, Saturn, and PS1 opened up whole new frontiers in gaming and paved the way for the games we have today. 

Of all the 3D games on this generation of consoles, which do you think was the most graphically impressive, and what about it made it so impressive?