What is best way to transfer data to new MAC

Some options:

• Migration Assistant, Move your content to a new Mac - Apple Support
• External drive
• Cloud service
• Shared Connection
• Network Drive
• FTP Server
• ...

Migration assistant or external drive are probably easiest to implement and will be faster.

a subtle refinement of the external drive solution is from the Backup drive of your old Mac.

If you are not already in the habit of maintaining a backup drive, you should know that each of:

• SSD drive

• soldered-in-place drive

• encrypted drive

... reduces the likelihood that you will be able to recover files after a disaster.

Back up your Mac with Time Machine - Apple Support

.