If you like shooters, GoldenEye and Perfect Dark's single player modes still hold up today. Jet Force Gemini's also pretty good, but it's more of a TPS/Metroidvania hybrid, and it can be pretty walkthrough inducing. Diddy Kong Racing is a unique single player Racing game. Blast Corps is okay, you should definitely look up gameplay before buying it. Conker can be expensive, and both the platforming and shooting segments pale in comparison to other Rare games of the time, so it might be best to just watch a walkthrough or let's play for the writing.
Now, moving on from Rare games, Bomberman Hero is an underrated 3D platformed similar to Super Mario 3D Land/World. The vehicle segments are straight up torture, but the regular levels are very fun. Paper Mario isn't quite as great as TTYD, but it's still easily the best RPG on the console. The Legend of Zelda Majora's Mask has the best writing in the series, and is a prime example of how some stories can only work in games and how the best stories in games aren't told through mandatory scenes. Pokemon Snap is a unique rails shooter, but it's very short.
Unfortunately, the N64 suffered from minimal third party support, poor sales, a short lifespan, and requiring all developers to publish their games to cartridges, so the library is very limited, especially from the 1999 onwards.
DLC? UGANDA WILL NOT HAVE THIS SICKNESS!