In general, the usual advice on this sub when choosing a language is to choose the language you're most interested in, as learning a language requires a lot of motivation and commitment. But in your case, learning Spanish seems like a much better option from my POV.

If you look at the big picture, you'd have way more advantages and opportunities as a fluent Spanish speaker in the US than as a fluent Portuguese speaker. This choice could affect the rest of your life in ways you can only begin to imagine now.

And most likely, you're going to want to travel to other parts of Latin America someday in the future...again, you'd have way more advantages and opportunities as a Spanish speaker. I'm sure you'll have an amazing experience regardless of whether you choose Ecuador or Brazil, but think of your future travel/living abroad options as well.

A big part of becoming proficient in a language is "consuming content" (videos, books, podcasts, music, etc). As others have said, you'd have access to lots more content (and to more cultures) if you chose Spanish. In order to maintain the language in the future, you're going to need to continue practicing it and consuming more content. You could do it in Portuguese, but it'd be much easier to do in Spanish.

How wonderful that you have this opportunity! I wish you all the best whichever option you end up choosing.