How long have they been in the field? What kind of education do they have? Work experience? Have they run any successful ICOs? Do they advise on any ICOs?
How many followers do they have? Where else do they write/speak? How does what they say influence the market at large?
How active are they on social? Are they one of the first to comment on breaking events? Do they respond to followers?
Do they only cover one topic/aspect or do they cover cryptocurrency and the blockchain as a whole? Are they focused on the crypto market or do they discuss finances at large?