i say n3ds but depends on what size you want

The super stable 3D display is worth it.

new 3ds

n3ds usually goes for a bit more because its rarer especially the NTSC version but if youre willing to spend more for the 3d effect and slightly easier time replacing the screen its worth it to you? i got my n2ds xl for around 220 on ebay in basically CIB so not terrible

white or black 3ds with cool color buttons

The New 2DS has a higher chance of hardware failure.

i went with new 3ds for the changeable face plates. they make them aftermarket now for like 30 bucks per pair of plates