Because you do a lot of travelling, I envision the Switch being ideal for you right now. You'll get a lot of play time out of Zelda and then soon enough there will be a bunch more games available.
I do love my Wii U, and contrary to what many will tell you, it does have games. But it is not the easiest system to travel with as you've gotta take the console, the power brick, the gamepad, the gamepad's power brick, the IR sensor, the games, and the controllers (and whatever else you may need). For right now, it does not seem like your ideal choice between the two. Plus, I envision its price could go down in the relatively near future, so "Switch now, Wii U later" is probably a cheaper overall proposition to "Wii U now, Switch later".