I nominate @tradeqwik, because it is an exchange like none other. It's the only exchange that blogs regularly. It accepts Steem and will accept SBD in the near future. It is attached to the VIVA project, which many Steemians are involved with. The account is operated by @wiser, who is another great person to follow.

Other great bloggers to follow are: @hanshotfirst for his sense of humour and generosity, and @lordvader for a great laugh and something unique to Steemit. :)