Bitcoin - Because bitcoin has been enjoying the king’s throne
Ethereum - Probably the safest
Ripple - Ripple seems to be the number one option for a lot of people because it is fast, well connected to bitcoin, and closely tied with financial institutions.
Iota - They are dedicated to B2B transactions.
Steem - I’d say steem is an exception because quality & curated content is a need of tomorrow. There is enough junk on the internet, perhaps putting in some faith into the steem platform would be worth it.