I disagree with this. Wii U was simply better built, designed better. Gamepad and Pro Controller had good ergonomics and worked well, good sticks, good d-pads, the charging stand for the Gamepad fits perfectly, Pro Controller has excellent battery etc...
Outside from the main tablet which is okay on Switch, everything is cheap and prone to issues. The stand is garbage, the console wiggles inside it. The rails to put the joycons will get loose after enough use. Sticks will drift. Joycons will disconnect. Joycon quality is bad, with super cheap plastic. The button layout on the joycons is abysmal because they wanted to have them usable as individual controllers. D-Pad is a complete joke. Pro Controller d-pad is awful as well. The piece of plastic for tabletop mode is ridiculously small. HDMI cable is super short too.
Unboxing a black Wii U really felt like having a good quality product, with everything that was well thought out. The Gamepad doesn't have the best quality screen of course and really that's the only thing were Switch feels better, but being a handheld at heart, it was the least it could do. Gamepad was still good enough as a secondary screen, and really nice to play all the retro games from the eShop. GBA games look very good on it. Unboxing a Switch feels like opening a toy. I was there day one for both systems.