That's a tricky question. I lived not only in Spain and Brasil but also Uruguay so I root for them also. My priorities are Spain, Brasil and Uruguay in that order. However, if anyone other than Spain is playing the USA, I'm rooting for the USA.
I sympathize with the protestors who are protesting the building of new stadiums and facilities when there are more pressing needs. I never thought Brasil was a great choice for that reason. However, it was the turn of a Latin American nation to host the WC and frankly none of them are in great shape. Something like a combination of Argentina and Brasil similar to what Japan and Korea did in 2002 would have made sense.
I also think that Qatar or the Middle East for 2022 (I believe) is foolish but there's a lot of corruption in FIFA.