The answer is simple; for now at least, the Wii U version of Breath of the Wild is far superior. The Switch version requires a £280 investment for entry (not including the game price) and it runs with significant frame rate drops if played on the TV screen. That is because the Switch isn't significantly more powerful than the Wii U and when running Zelda on the big screen, it does so at 900p. Granted that problem vanishes when you Switch (annoying click sound) to the tablet - but the Wii U side-hops the issue by just pushing the game out at 720p regardless of whether you're on the gamepad or TV.
That's before we've even taken into account the Switch's horrible teething problems; such as the de-syncing joycon (hmm 'con' I see what you did there Ninty) and the numerous glitches and bricked systems.
Yes Nintendo might fix the Switch, but right now there's only one format worth playing it on. That said - even if Nintendo fix their dubious new hardware - there's a new contender in the arena; CEMU. In just a matter of days, the boys at CEMU have taken their emulator from a state in which it wouldn't run BotW at all, to booting into the menu screen - and now (using the latest version) you can actually run the game - albeit with choppy frame-rate, no sound and numerous glitches. But the future looks bright. CEMU will already run the Mario stable of Wii U titles at 60 fps and 4k (providing you PC has the grunt) so I know which format I'll be playing my second round of BotW on. Aint life a switch Nintendo!