Sia is an already working technology that is rapidly improving (https://blog.sia.tech/sia-may-august-2017-update-8929f21c56f7 ), filecoin on the other hand only exists in theory (whitepaper).

Siacoin was fairly launched and distributed. The filecoin ICO unfortunately seems to favour a limited number of its inner circle investors ( https://medium.com/token-economy/the-analysis-filecoin-doesnt-want-you-to-read-e60d5243f17c )