What was the best-selling Nintendo 64 game of all time?

What was the best-selling Nintendo 64 game of all time?
Tenor

If we're talking home video consoles based purely on bits, it's hard to argue with the sheer computing power that was the N64. Well, if you're comparing it to the original 8-bit NES, at least.

You have to give credit to Nintendo for always sticking to their guns. When everyone else was moving towards disc-based consoles, they released the cartridge-based Nintendo 64 and didn't shy away from their gradual ramp-up of bits that had defined the Console Wars up to that point.

And somehow they competed — at least in terms of great exclusive games. It's easy to argue that many of the best console games of all time came out for the N64.

This one was not only groundbreaking in its time, but moved a lot of units, as we say in the biz. Which game was it?