I'm at the point in my novel that I am shopping for ageents. The agency I am most interested in allows mail or email submissions. I've always been an instant gratification person, but is there a preferred media?
You always submit according the the agent's (or publisher's) requirements. Frankly, if you're addicted to instant gratification, writing is not your field.
Well, I've been kicking this idea for ten years or so, but thanks for your concern over my mental health.
if you haven't got a completed, edited-to-perfection ms ready to submit, then you're not ready to shop for agents...
This website allows you to search for agents based on their submission methods and their genre. http://www.agentquery.com/ Remember rejections come quickly and requests come slow. Sometimes you can get a rejection for an email query the same day you sent it! However requests for material will generally take a few weeks. When they have your material, it will take them a few months to read it. Good luck!