Which system made the biggest comeback? PlayStation 4 or Nintendo Switch?

[Kyuu]

PS4 was definitely a "comeback" that also enabled Sony to be among the biggest names in software, far bigger than they ever were.

The Switch was the bigger surprise, but you can't compare it to older systems as directly as you can with Playstation, because it's a hybrid unlike anything else Nintendo released before. Still, it managed to easily outsell Wii U and 3DS combined, and made a ton more money for Nintendo. So it's totally the bigger comeback all things considered.