Migrating to a new Macbook with data on an external SSD.

What data is transferred with the migration assistant "select information to transfer" options? I am moving to a new Macbook. My data is on an external SSD (including my photos and mucic library). I back this external SSD and everything on the Macbook itself to a second SSD using Time Machine.

What is the best way to migrate to the new Macbook? I want to move everything as it currently exists to the new Macbook platform.

Thanks for your ideas!