Hello, @GenghisKen

Hope you’re well!

• The migration option to move your data to a new server/droplet is considered a lot more safe as you can test if your site/application is properly working from the new environment (you can fully test everything before “pushing” your site live from the new server). Also this process is not really complex as you can move the site/application files and database using many tools like FTP/sFTP. rsync, scp to the new server and then just configure the rest of the server configurationlike web server, database engine and so on.

You do not need to copy all the files from /etc /var /opt

You can simply deploy the new droplet and then migrate the content of your site/application and test if everything is working as expected.

• Where on the other side if you go and try to upgrade the OS a lot of things can go wrong and you might end up losing your data and break the server configuration. You can of course take a backup of your files download it locally and also create a snapshot of the droplet and then go ahead and try to upgrade the OS.

Note: You need to take a full backup of your files and databases before going with any of the two options. You can then copy the backup locally on your machine in order to make sure you have the backup available in case something goes wrong and you can’t connect to the server.
It is really important to have a working copy of the server config files as well in case you have a custom setup of the web server or of the database engine as well. You can do a quick copy of the most important files and save them locally as well, as you might need them when you tweak the configuration on the new server.

Hope this helps!

Regards,
Alex