SNES + Gameboy slightly edging out Switch for me.

Switch

The games, the hardware, the seamless simplicity of using the system... there isn't another experience, in my opinion, that reaches the Switch. It's the pinnacle of the Nintendo Console/Handheld experience.

Switch, obviously. They took all their resources, combined them, and created a unified, streamlined powerhouse that has a chance to become the most popular piece of hardware in the company's history... nearly forty years after the NES! That's really saying something.

Gamecube games are making their way to Switch now, most recently Story of Seasons: A Wonderful Life, and Baten Kaitos later this year. I'm enjoying that. A lot of stuff that never appeared on Virtual Console on Wii or Wii U also made it to Switch through retro game collections. I'm still hoping for FE: Path of Radiance. I have accepted that Wind Waker and Twilight Princess are likely to be holdouts for the Switch 2.

Some of my favorites are all the original Nintendo arcade games like Donkey Kong that weren't released before due to legal snags between Nintendo and the manufacturer.

Plus, it has most of my favorites from 7th gen as well, namely, Valkyria Chronicles, Ni no Kuni, Tales of Vesperia, and Xenoblade Chronicles. 

Switch is not only my favorite combo, but it's my favorite dedicated gaming system of all time. I have bought more games for Switch than for I have for every PlayStation system combined, and previously the PS1 was the system that I bought the single most games for. Combine the retro stuff with games like BotW, TotK, Fire Emblem: TH and Engage, Mario Odyssey, Dragon Quest XI S, SMT V, Persona, Valkyria Chronicles 4, Witcher 3, No Man's Sky, and its library is unparalleled.

Of the other options, I vote fro GC + GBA. I still use the GB Player, and I loved the Gamecube, which reminded me of why I loved Nintendo games after N64 let me down.

Of finished libraries, it's probably GCN and GBA. But Switch as a whole simply has more first and third-party experiences I care about than either of those platforms.

Personally I've never been hugely into handhelds, though I have dabbled in them occasionally, but the SNES remains my #1 system of all time so my vote had to go there.

That said, Switch is getting very damn close at this point, having built up an exemplary library, plus the convenience of having all Nintendo's output on one machine is just awesome.
About the only thing holding Switch back from being the all time greatest in my view is that it's missing new games from a few key IPs, but that's a small downside compared to all that it does offer.

Wii+DS is redundant as the WiiU+3DS can pretty much play that entire library and then it's own.

For me SNES+Gameboy, it's what I had as a teenager and I have many fond memories. Rose tinted glasses.

Wii + DS can play Gamecube games, something the WiiU + 3DS combo cannot. The GBA library is a lot smaller on WiiU virtual console as well compared to the full library of GBA games playable on DS.

I think the addition of Gamecube and GBA games is more worth than the 3DS and WiiU library, if Wii and DS games is playable in both constellations. But I'm a bit biased and did not enjoy much of the WiiU and 3DS library. Still would not call the combo redundant. 

It's literally what Switch was designed for