Secondary essay or AMCAS essay - which is more important?

For the vast majority of schools the Personal Statement carries considerably more weight than secondary essays. There are some like UofC, Duke, and a couple top 10s that make a really big deal out of them but for the most part, the PS is king. Most secondaries ask for brief responses to their questions so the key is to get the point quickly with them and to turn them in quickly. Again though, there are a few exceptions like UofC's which is a pain in the butt.

 

More important? It's hard to say, since both are integral to your total application package. The AMCAS essay needs to give the admissions committee a picture of you as an interesting human being, not just a collection of numbers, classes, and achievements. The secondary essays should build on this picture, flesh it out more, and seamlessly complement the rest of your application. Saying that one piece is more important than the other is too simplistic. They both should make the admissions committee want to meet you in person.