What is the #1 prescribed migraine medication?

Could you elaborate on what the most commonly prescribed migraine medication is? As someone who is familiar with the field of healthcare and pharmacology, I'm curious to know which drug is typically recommended by doctors as the first-line treatment for managing migraines. Is there a specific class of medications that stands out, or is it a particular brand name that is widely prescribed? It would be great if you could provide some insights into the effectiveness and potential side effects of this medication as well.