Upvote:4
T-Mobile has a unlimited-data-in-120+-countries plan that should cover all your countries. I have that plan since two years, and it worked smoothless (and cost-free) in India, Russia, all of Western Europe, Czechia, the Carribean, Mexico, Canada and the US.
Note that some countries or areas do not have 4G/LTE, and no matter what you buy or do, you will not get 4G/LTE speed there.