What's the best way to transfer data to a new Mac?

Use Migration Assistant with a Thunderbolt cable — it’s the fastest and most reliable way. Both Macs need to be on the same Wi-Fi or connected via Thunderbolt (or USB-C to USB-C) and running macOS Monterey or later. It copies everything: apps, files, settings, even your wallpaper. If you don’t have a cable, Wi-Fi works but is slow, or you can use a Time Machine backup.