Senlis on 28 March 2009
That is a tough decision. PS1 had a lot more games, but there are a few games on the N64 that really shine such as Mario 64, Goldeneye, Harvest Moon 64, Star Fox 64, Ocarina of Time, Manjora's Mask.
If I could only have one, I would have to have the N64. Of course, I own both.