Should I get Breath of the Wild on Wii U?

Yes, you should get Breath of the Wild on Wii U.

If you already have a Wii U & no interest in getting a Switch, go ahead & get Zelda: Breath of the Wild on the Wii U as it's a great game that breaks some of the Zelda traditions.

If you're planning on getting a Switch, you might want to wait... mostly to avoid double-dipping unless you really want it on both (You do you here).

Twilight Princess & Wind Waker HD are pretty good as well the other Zelda titles that are available on the Wii U through the Virtual Console service (Skyward Sword, Minish Cap, Phantom Hourglass, Spirit Tracks, Ocarina of Time, Majora's Mask) that are not available on the Switch at this time.

I will note that there's a post-game area in Twilight Princess called the "Cave of Shadows" that can be access with the Wolf Link amiibo.  If you can make it through all 40 floors, whatever health you have left (as you'll be able to save your status on the amiibo) will become Wolf Link's Health in Breath of the Wild when you scan that amiibo.

Wolf Link in Breath of the Wild serves as a helper character (like a loyal dog, albeit from a different but parallel universe / time line / ect.).  They'll attack enemies nearby, provide some defense to Link & search for hidden treasure.  Once their health is exhausted, they'll disappear & cannot be re-summoned for the rest of the day (at the game ties amiibo scans to the current date).

If you already have a Wii U but don't have a Switch... I guess?

It's not worth hunting down a Wii U for since the Switch version is much easier to find and generally runs better.

Not sure it's worth it I say no