Transferring everything from one Mac to another should be relatively simple except when Migration Assistant cannot access your Time Machine Backup. This might be the case for people backing up to networked attached hard drives. I don’t think this would be an issue though for a Time Machine backup on a Time Capsule. I went through the endless solutions at “Migration Assistant can’t find my hard drive – can you help?” with no luck.
If you don’t have the above issue then following the instructions in the article “Move your content to a new Mac” or “Move content to your new MacBook or late-2016 MacBook Pro“will work beautifully. For newer If you are among the unlucky though, then the simplest way would be to backup directly to an attached portable hard drive then plugging that hard drive to the new Mac (I have not tried this method personally though). The way I did it was to use an Apple Thunderbolt Cable (longer cable here). Worked like a charm.. refer to the awesome video below to help guide you through the process.