3DS gets so underrated on this forum and some other forums.
We got the best Animal Crossing up to its time (and basically a game that is equal to New Horizons), a portable Smash, Fire Emblem Awakening, Fire Emblem: Fates, Zelda: Ocarina of Time 3D, Zelda: A Link Between Worlds, Mario Kart 7, Super Mario 3D Land, Kid Icarus Uprising, and some others.
Even if we remove ports and remakes from the 3DS first-party line=up, it probably beats the Switch's first-party lineup (again excluding ports and remakes). But that isn't fair, because Switch still has years left (hence why it's excluded in this poll).
The 3DS is the first Nintendo handheld to nail 3D gaming (no, not the 3D effect). For the most part, 3D games on the DS were originally an afterthought. But Nintendo actually bumped up a few specs of the DS after seeing some of the PSP's specs, and made sure to have some 3D titles available.
Lifetime Sales Predictions
Switch: 144 million (was 73, then 96, then 113 million, then 125 million)
PS5: 105 million Xbox Series S/X: 60 million
PS4: 120 mil (was 100 then 130 million, then 122 million) Xbox One: 51 mil (was 50 then 55 mil)
3DS: 75.5 mil (was 73, then 77 million)
"Let go your earthly tether, enter the void, empty and become wind." - Guru Laghima