How Do I Get Everything From Old MacBook Onto New MacBook If Apple Has It?

I want to turn in my mid-2012 Macbook to Apple and buy a new Macbook, applying whatever credit Apple gives me for the old MB toward the cost of the new MB. In the past I’ve simply hooked up the two computers and used Migration Assistant. And, of course, I have Time Machine as well as SuperDuper! backups that I can use to load the files onto the new MB. But never having done this before, I want to be sure I’m proceeding correctly.
Any advice will be very much appreciated. (And many thanks for all the advice you’ve given to me and others over the year via Macmost.)
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Andy Hinds