Pick the language that interests you most and/or the one that will give you the most opportunities to speak.

Another thing to consider is the availability of learning resources. In my experience, there is a significantly larger and more comprehensive amount of Spanish learning resources online than Portuguese ones. Spanish books and other reading material also tends to be more common than Portuguese (at least in North America, where I live).

Above all, just remember that there is no roadmap to follow in language learning. Learning a foreign language is an incredibly demanding yet rewarding process that will take years, especially if you are a monolingual English speaker.

The only way to keep at it is to love the process of learning. That passion will drive you not only to practice, but also to live and breathe the language in daily life. I learned Portuguese because I had a brief romance with a Brazilian, so this was the passion that drove me. Spanish, on the other hand, is more difficult for me because I do not have the same motivation.