Include both agents and publishers in your submission strategy, going heavy on the agents. Most agents accept submissions from everybody; it’d be unwise to turn your back on that fact. Submit to as many as are appropriate for your manuscript. Also attend conferences or events where editors are present. They often extend open submission invites to attendees, getting you past their “no unsolicited mss” policies. (Yes, most publishers have those.) If you land a publisher first, agents will be more likely to represent you because clearly your work is marketable. If an agent bites first, then you’ve got access to her speed dial—and you’ve got someone who can handle your contract and help you shape your career.