Personally I used the migration assistant to get everything from my MM to the new iMac, Cat6 ethernet cable and followed the directions. I'd suggest a thunderbolt cable if you have one, I thought I did but didn't so i used the Cat6 which I believe is the next fastest option. Took about few give or take to complete the whole process from boot to transfer to using the iMac, my MM had a little over 500gb on internal HDD. If your internals are SSD it might even be faster.
Pretty sure you could use some other apps like carbon copy or another drive cloning app and get it done as well, and I'm sure there is another thread about migration assistant and other options too with some pretty good info too.
Here ya go
https://forums.macrumors.com/threads/using-migration-assistance.1929810/