I think the best social media for the ico campaign is of course the bitcoin forum because in this forum it contains people who are most interested in the crypto world than on other social media. So to campaign ico to be more efficient. But that does not mean campaigning with other social media will not advance, if seen from the number of users without a background view only speculate from the many users may facebook and instagram can be used as an alternative.
Indeed, the number of people who are aware of cryptocurrencies is and will be growing, a lot of communities are born around this topic across all social media, so reaching out to them in that environment seems to be a good idea as well.