So, you have mastered Spanish and are ready for the next linguistic challenge. Do you learn Chinese, Arabic, or Pashtun? Language acquisition (LA) is like any other skill, the more you practice, the better you get.
Before committing to a thousand hours of Chinese classes, try honing your skills with a smaller step towards Portuguese. This way, when you do commit to some of the more complex languages, your language learning ability will be well-practiced and streamlined.