And for those of you who had neither, what about the Switch appealed to you where both Wii U and 3DS didn't?

I've only owned a Gameboy SP (NES edition) and I borrowed my gf's DSLite on occasion. I've always been more of a console gamer.  The only Nintendo console I've missed was the N64.

Yes, I have both.

I had both, I got a Wii U in 2013 and a 2DS very late in 2019

Both, yeah.

I got the WiiU quite late in its lifetime.

Both and I like them more than the Switch.

I preferred WiiU to Switch, though I thought the giant Gamepad was weird. I owned at 3DS, but was never a big fan of it. I think I bought it after that price break near launch because I knew I would be laid up for a while and wanted something convenient to play without having to get out of bed. But, before I sold it in 2018, I probably only ever purchased 6-8 games for it.

I had them both. The funny thing is that I bought the 3ds two months after the launch of Switch and the Wii U at 6 months.

Why not before?

R/ Because I had no money

Why just in the year of Switch launch?

R/ The Switch and Zelda BOTW aroused my curiosity. So I wanted to play most Zeldas before playing BOTW. I started playing TLOZ A link
to the Past. I loved the game and wanted more and the best way to play many Zelda games was with Wii U + 3ds. I played on the Wii U to Wind Waker, Twilight Princess and I was planning to play Skyward Sword but the game was damaged right at the moment you jump into the world below.
In 3ds I could play Ocarina of Time and A Link Between Worlds. After 1 year, play Zelda BOTW on Wii U. And the following year I bought the Switch. Later I plan to buy BOTW again but this time on Switch. I definitely want to return to that world.

The Wii U and the 3ds were the first consoles I had from Nintendo since the time of NES / SNES. I didn't have the rest because I didn't have money. That said, I definitely loved the time I had the Wii U and also the 3ds. Both have given me incredible experiences. Oh and needless to say that I not only played the Zeldas, I played many other games on both consoles.

Both, and loved them both

Still do. 3DS XL in 2012 and a Wii U in 2013. While I have some good games on both. I hate using the hardware on both. It's just crap to use. Awful UI on both but at least I have custom SEGA themes on 3DS. Gamepad on Wii U is shit to use tho. I hate it. Anytime I can use the pro controller I did. We still need Xenoblade X to come to Switch.