it really depends on why you want to learn the language in the first place, is it for like a hobbie or for jobs or something in the future....
if u learn chinese, it would probably help you a lot in future.
a lot of people speaks spanish, but it's really not dat important though right now in the world. and more and more people are speaking chinese, it would probably be like how much people speaking english right now, in the future..
learning chinese is hard, but it'll be very profitable.so it's really your choice, depending on your reason for wanting to learn Spanish or Chinese.
i am learning japanese now, because i think it's really cool and i want to get a job in japan.