Hi There
let me tell you first that I am french... but I'll try to give you an objective point of view.
Spanish is far more spoken than french of course, mainly because of south and central america (where everybody speaks spanish except Brazil) and because of the huge spanish community in the USA.
That is probably why spanish would help you more in the future.
However it depends on what you're willing to do in the future. French used to be the language for diplomacy, it is mainly spoken in Northern america in Québec, in Africa.
I don't think there is an easier one between those two, they are both latin rooted languages, they look like each other in structure. French has the reputation to be very difficult though.
Hope that helps... even though I would have a lot more to say about those languages
