It depends on how much stock you put into original, current-gen software.
In terms of pure library, it's hard to argue against Switch being #1, especially when the system has no backwards compatibility. You've got native versions of the best NES, SNES and soon-to-be N64 and Genesis games. You've got the full Neo Geo library. A lot of the best third-party games of the past three decades are getting re-releases. Most of the Wii U's best games have been ported over. And after all that, you've got some pretty strong showings from Nintendo's first party + indies + a decent amount of mid-tier-and-below Japanese third party software (more on that later).
If you value original content, however, I think the Switch is a solid B+. Nintendo has relied a lot on Wii U ports to fill out the library. As a result, we've yet to see an original Mario Kart, 2D Mario or Donkey Kong game, and we're just now starting to see revivals of beloved franchises (Metroid, Advance Wars), and active mid-tier series getting major leaps forward (Paper Mario Origami King, Kirby and the Forgotten Land). It also seems like EPD have cooled down on their 'traditional gaming' new IP initiative after ARMS seemingly failed to meet their lofty expectations.
Third parties have also been mediocre - western studios are one thing but with how strong sales have been in Japan from the start, I was expecting a much stronger software pipeline by now, with a good amount of more experimental and/or mid-tier software aimed at the Switch, then up-ported to the other platforms. Instead, it has sort of picked up where the 3DS and a more successful Vita would have left off... and that's about it, with some former notable Vita devs (Falcom, Vanillaware) having to be dragged kicking and screaming to support the platform. Sega has yet to release a single new, high-effort project on the system. Namco are mostly doing old ports. After porting most of their classic FF catalog, Square-Enix seem content with putting out HD-2D nostalgia-bait. Ironically, Capcom, who arguably have the least to lose by sidelining Japan after Monster Hunter World sold more than the three previous mainline games combined, also have the strongest Switch pipeline if the list of games leaked through the hack is to be believed.
As for me, I think the Switch is just a tier below the SNES and DS.