Should I learn Portuguese or Spanish first?

I want to learn both the Spanish (Latin-American/Mexican) and Portuguese languages, since nationality-wise, i’m half of both. Over the years i’ve learned bits of each language, but I was never very serious about it. Now I want to learn each fluently, but i’m not sure which one to begin with first. I know some accents are more difficult than others, so which would be the better to start?